diff --git a/MANIFEST.in b/MANIFEST.in
index a029c65..f867763 100644
--- a/MANIFEST.in
+++ b/MANIFEST.in
@@ -1,2 +1,2 @@
-graft config
+include aws_doc_sdk_examples_tools/config/*.yaml
 
diff --git a/config/.yamllint.yaml b/aws_doc_sdk_examples_tools/config/.yamllint.yaml
similarity index 100%
rename from config/.yamllint.yaml
rename to aws_doc_sdk_examples_tools/config/.yamllint.yaml
diff --git a/config/curated_example_schema.yaml b/aws_doc_sdk_examples_tools/config/curated_example_schema.yaml
similarity index 100%
rename from config/curated_example_schema.yaml
rename to aws_doc_sdk_examples_tools/config/curated_example_schema.yaml
diff --git a/config/example_schema.yaml b/aws_doc_sdk_examples_tools/config/example_schema.yaml
similarity index 100%
rename from config/example_schema.yaml
rename to aws_doc_sdk_examples_tools/config/example_schema.yaml
diff --git a/config/example_strict_schema.yaml b/aws_doc_sdk_examples_tools/config/example_strict_schema.yaml
similarity index 100%
rename from config/example_strict_schema.yaml
rename to aws_doc_sdk_examples_tools/config/example_strict_schema.yaml
diff --git a/config/sdks.yaml b/aws_doc_sdk_examples_tools/config/sdks.yaml
similarity index 100%
rename from config/sdks.yaml
rename to aws_doc_sdk_examples_tools/config/sdks.yaml
diff --git a/config/sdks_schema.yaml b/aws_doc_sdk_examples_tools/config/sdks_schema.yaml
similarity index 100%
rename from config/sdks_schema.yaml
rename to aws_doc_sdk_examples_tools/config/sdks_schema.yaml
diff --git a/config/services.yaml b/aws_doc_sdk_examples_tools/config/services.yaml
similarity index 100%
rename from config/services.yaml
rename to aws_doc_sdk_examples_tools/config/services.yaml
diff --git a/config/services_schema.yaml b/aws_doc_sdk_examples_tools/config/services_schema.yaml
similarity index 100%
rename from config/services_schema.yaml
rename to aws_doc_sdk_examples_tools/config/services_schema.yaml
diff --git a/aws_doc_sdk_examples_tools/doc_gen.py b/aws_doc_sdk_examples_tools/doc_gen.py
index 68809f6..33052f5 100644
--- a/aws_doc_sdk_examples_tools/doc_gen.py
+++ b/aws_doc_sdk_examples_tools/doc_gen.py
@@ -5,26 +5,31 @@
 
 from dataclasses import dataclass, field
 from pathlib import Path
-from typing import Dict, List, Optional, Set
+from typing import Dict, Iterable, Optional, Set
 
 # from os import glob
 
-from aws_doc_sdk_examples_tools.metadata import Example, parse as parse_examples
-from aws_doc_sdk_examples_tools.metadata_errors import MetadataErrors
-from aws_doc_sdk_examples_tools.metadata_validator import validate_metadata
-from aws_doc_sdk_examples_tools.project_validator import (
+from .metadata import Example, parse as parse_examples
+from .metadata_errors import MetadataErrors, MetadataError
+from .metadata_validator import validate_metadata
+from .project_validator import (
     check_files,
     verify_sample_files,
 )
-from aws_doc_sdk_examples_tools.sdks import Sdk, parse as parse_sdks
-from aws_doc_sdk_examples_tools.services import Service, parse as parse_services
-from aws_doc_sdk_examples_tools.snippets import (
+from .sdks import Sdk, parse as parse_sdks
+from .services import Service, parse as parse_services
+from .snippets import (
     Snippet,
     collect_snippets,
     validate_snippets,
 )
 
 
+@dataclass
+class DocGenMergeWarning(MetadataError):
+    pass
+
+
 @dataclass
 class DocGen:
     root: Path
@@ -33,68 +38,148 @@ class DocGen:
     services: Dict[str, Service] = field(default_factory=dict)
     snippets: Dict[str, Snippet] = field(default_factory=dict)
     snippet_files: Set[str] = field(default_factory=set)
-    examples: List[Example] = field(default_factory=list)
+    examples: Dict[str, Example] = field(default_factory=dict)
     cross_blocks: Set[str] = field(default_factory=set)
 
-    def collect_snippets(self, snippets_root: Optional[Path]):
+    def collect_snippets(
+        self, snippets_root: Optional[Path] = None, prefix: Optional[str] = None
+    ):
+        if prefix is not None:
+            prefix = f"{prefix}_"
+        if prefix is None:
+            prefix = ""
         if snippets_root is None:
-            snippets_root = self.root.parent.parent
-        snippets, errs = collect_snippets(snippets_root)
+            snippets_root = self.root
+        snippets, errs = collect_snippets(snippets_root, prefix)
         self.snippets = snippets
         self.errors.extend(errs)
 
+    def languages(self) -> Set[str]:
+        languages: Set[str] = set()
+        for sdk_name, sdk in self.sdks.items():
+            for version in sdk.versions:
+                languages.add(f"{sdk_name}:{version.version}")
+        return languages
+
+    def merge(self, other: "DocGen") -> MetadataErrors:
+        """Merge fields from other into self, prioritizing self fields"""
+        warnings = MetadataErrors()
+        for name, sdk in other.sdks.items():
+            if name not in self.sdks:
+                self.sdks[name] = sdk
+            else:
+                warnings.append(
+                    DocGenMergeWarning(
+                        file=str(other.root), id=f"conflict in sdk {name}"
+                    )
+                )
+        for name, service in other.services.items():
+            if name not in self.services:
+                self.services[name] = service
+                warnings.append(
+                    DocGenMergeWarning(
+                        file=str(other.root), id=f"conflict in service {name}"
+                    )
+                )
+        for name, snippet in other.snippets.items():
+            if name not in self.snippets:
+                self.snippets[name] = snippet
+                warnings.append(
+                    DocGenMergeWarning(
+                        file=str(other.root), id=f"conflict in snippet {name}"
+                    )
+                )
+
+        self.snippet_files.update(other.snippet_files)
+        self.cross_blocks.update(other.cross_blocks)
+        self.extend_examples(other.examples.values())
+
+        return warnings
+
+    def extend_examples(self, examples: Iterable[Example]):
+        for example in examples:
+            id = example.id
+            if id in self.examples:
+                self.examples[id].merge(example, self.errors)
+            else:
+                self.examples[id] = example
+
     @classmethod
-    def from_root(cls, root: Path) -> "DocGen":
-        errors = MetadataErrors()
+    def empty(cls) -> "DocGen":
+        return DocGen(root=Path("/"), errors=MetadataErrors())
+
+    def clone(self) -> "DocGen":
+        return DocGen(
+            root=self.root,
+            errors=MetadataErrors(),
+            sdks={**self.sdks},
+            services={**self.services},
+            snippets={},
+            snippet_files=set(),
+            cross_blocks=set(),
+            examples={},
+        )
 
+    def for_root(self, root: Path, config: Optional[Path] = None) -> "DocGen":
+        self.root = root
         metadata = root / ".doc_gen/metadata"
 
-        with open(
-            Path(__file__).parent.parent / "config" / "sdks.yaml", encoding="utf-8"
-        ) as file:
+        if config is None:
+            config = Path(__file__).parent / "config"
+
+        with open(config / "sdks.yaml", encoding="utf-8") as file:
             meta = yaml.safe_load(file)
             sdks, errs = parse_sdks("sdks.yaml", meta)
-            errors.extend(errs)
+            self.errors.extend(errs)
 
-        with open(
-            Path(__file__).parent.parent / "config" / "services.yaml", encoding="utf-8"
-        ) as file:
+        with open(config / "services.yaml", encoding="utf-8") as file:
             meta = yaml.safe_load(file)
             services, service_errors = parse_services("services.yaml", meta)
-            errors.extend(service_errors)
+            self.errors.extend(service_errors)
 
         cross = set(
             [path.name for path in (metadata.parent / "cross-content").glob("*.xml")]
         )
 
-        doc_gen = cls(
-            root=root,
-            sdks=sdks,
-            services=services,
-            errors=errors,
-            cross_blocks=cross,
-        )
+        self.root = root
+        self.sdks = sdks
+        self.services = services
+        self.cross_blocks = cross
 
         for path in metadata.glob("*_metadata.yaml"):
             with open(path) as file:
-                ex, errs = parse_examples(
+                examples, errs = parse_examples(
                     path.name,
                     yaml.safe_load(file),
-                    doc_gen.sdks,
-                    doc_gen.services,
-                    doc_gen.cross_blocks,
+                    self.sdks,
+                    self.services,
+                    self.cross_blocks,
                 )
-                doc_gen.examples.extend(ex)
-                errors.extend(errs)
+                self.extend_examples(examples)
+                self.errors.extend(errs)
+                for example in examples:
+                    for lang in example.languages:
+                        language = example.languages[lang]
+                        for version in language.versions:
+                            for excerpt in version.excerpts:
+                                self.snippet_files.update(excerpt.snippet_files)
+
+        return self
 
-        return doc_gen
+    @classmethod
+    def from_root(cls, root: Path, config: Optional[Path] = None) -> "DocGen":
+        return DocGen.empty().for_root(root, config)
 
     def validate(self, check_spdx: bool):
+        for sdk in self.sdks.values():
+            sdk.validate(self.errors)
+        for service in self.services.values():
+            service.validate(self.errors)
         check_files(self.root, self.errors, check_spdx)
         verify_sample_files(self.root, self.errors)
         validate_metadata(self.root, self.errors)
         validate_snippets(
-            self.examples,
+            [*self.examples.values()],
             self.snippets,
             self.snippet_files,
             self.errors,
diff --git a/aws_doc_sdk_examples_tools/metadata.py b/aws_doc_sdk_examples_tools/metadata.py
index a099e8d..75fd4a7 100755
--- a/aws_doc_sdk_examples_tools/metadata.py
+++ b/aws_doc_sdk_examples_tools/metadata.py
@@ -9,14 +9,15 @@
 from os.path import splitext
 
 from aws_doc_sdk_examples_tools import metadata_errors
-from aws_doc_sdk_examples_tools.metadata_errors import (
+from .metadata_errors import (
+    MetadataError,
     MetadataErrors,
     MetadataParseError,
     DuplicateItemException,
 )
-from aws_doc_sdk_examples_tools.metadata_validator import StringExtension
-from aws_doc_sdk_examples_tools.services import Service
-from aws_doc_sdk_examples_tools.sdks import Sdk
+from .metadata_validator import StringExtension
+from .services import Service
+from .sdks import Sdk
 
 
 @dataclass
@@ -64,10 +65,10 @@ class Version:
     excerpts: List[Excerpt] = field(default_factory=list)
     # Link to the source code for this example. TODO rename.
     github: Optional[str] = field(default=None)
-    add_services: Dict[str, List[str]] = field(default_factory=dict)
+    add_services: Dict[str, Set[str]] = field(default_factory=dict)
     # Deprecated. Replace with guide_topic list.
     sdkguide: Optional[str] = field(default=None)
-    # Link to additional topic places. TODO: Overwritten by aws-doc-sdk-example when merging.
+    # Link to additional topic places.
     more_info: List[Url] = field(default_factory=list)
 
     @classmethod
@@ -143,6 +144,22 @@ class Language:
     name: str
     versions: List[Version]
 
+    def merge(self, other: "Language", errors: MetadataErrors):
+        """Add new versions from `other`"""
+        # TODO Error for mismatched names?
+        if self.name != other.name:
+            return
+        for other_version in other.versions:
+            self_version = filter(
+                lambda v: v.sdk_version == other_version.sdk_version, self.versions
+            )
+            if self_version is None:
+                self.versions.append(other_version)
+            # Merge down to the SDK Version level, so later guides can add new
+            # excerpts to existing examples, but don't try to merge the excerpts
+            # within the language. If a tributary or writer feels they need to
+            # modify an excerpt, they should go modify the excerpt directly.
+
     @classmethod
     def from_yaml(
         cls,
@@ -177,6 +194,12 @@ def from_yaml(
         return cls(name, versions), errors
 
 
+@dataclass
+class ExampleMergeMismatchedId(MetadataError):
+    other_id: str = ""
+    other_file: str = ""
+
+
 @dataclass
 class Example:
     id: str
@@ -195,10 +218,39 @@ class Example:
     # TODO document service_main and services. Not to be used by tributaries. Part of Cross Service.
     # List of services used by the examples. Lines up with those in services.yaml.
     service_main: Optional[str] = field(default=None)
-    services: Dict[str, List[str]] = field(default_factory=dict)
+    services: Dict[str, Set[str]] = field(default_factory=dict)
     synopsis_list: List[str] = field(default_factory=list)
     source_key: Optional[str] = field(default=None)
 
+    def merge(self, other: Example, errors: MetadataErrors):
+        """Combine `other` Example into self example.
+
+        Merge down to the SDK Version level, so later guides can add new excerpts to existing examples, but don't try to merge the excerpts within the language.
+        If a tributary or writer feels they need to modify an excerpt, they should go modify the excerpt directly.
+
+        Keep title, title_abbrev, synopsis, guide_topic, category, service_main, synopsis_list, and source_key from source (typically awsdocs/aws-doc-sdk-examples).
+        !NOTE: This means `merge` is NOT associative!
+
+        Add error if IDs are not the same and return early.
+        """
+        if self.id != other.id:
+            errors.append(
+                ExampleMergeMismatchedId(
+                    id=self.id, other_id=other.id, file=self.file, other_file=other.file
+                )
+            )
+            return
+
+        for service, actions in other.services.items():
+            if service not in self.services:
+                self.services[service] = actions
+
+        for name, language in other.languages.items():
+            if name not in self.languages:
+                self.languages[name] = language
+            else:
+                self.languages[name].merge(language, errors)
+
     @classmethod
     def from_yaml(
         cls,
@@ -212,16 +264,20 @@ def from_yaml(
         title = get_with_valid_entities("title", yaml, errors)
         title_abbrev = get_with_valid_entities("title_abbrev", yaml, errors)
         synopsis = get_with_valid_entities("synopsis", yaml, errors, opt=True)
+        synopsis_list = [str(syn) for syn in yaml.get("synopsis_list", [])]
 
-        category = yaml.get("category", "")
         source_key = yaml.get("source_key")
-        parsed_services = parse_services(yaml.get("services", {}), errors, services)
-        synopsis_list = [str(syn) for syn in yaml.get("synopsis_list", [])]
         guide_topic = Url.from_yaml(yaml.get("guide_topic"))
         if isinstance(guide_topic, MetadataParseError):
             errors.append(guide_topic)
             guide_topic = None
 
+        parsed_services = parse_services(yaml.get("services", {}), errors, services)
+        category = yaml.get("category")
+        if category is None or category == "":
+            category = "Api" if len(parsed_services) == 1 else "Cross"
+        is_action = category == "Api"
+
         service_main = yaml.get("service_main", None)
         if service_main is not None and service_main not in services:
             try:
@@ -229,11 +285,6 @@ def from_yaml(
             except DuplicateItemException:
                 pass
 
-        if category == "":
-            category = "Api" if len(parsed_services) == 1 else "Cross"
-
-        is_action = category == "Api"
-
         yaml_languages = yaml.get("languages")
         languages: Dict[str, Language] = {}
         if yaml_languages is None:
@@ -267,20 +318,24 @@ def from_yaml(
 
 def parse_services(
     yaml: Any, errors: MetadataErrors, known_services: Dict[str, Service]
-) -> Dict[str, List[str]]:
+) -> Dict[str, Set[str]]:
     if yaml is None:
         return {}
-    services: Dict[str, List[str]] = {}
+    services: Dict[str, Set[str]] = {}
     for name in yaml:
         if name not in known_services:
             errors.append(metadata_errors.UnknownService(service=name))
         else:
-            service: Dict[str, None] | None = yaml.get(name)
+            service: Dict[str, None] | Set[str] | None = yaml.get(name)
             # While .get replaces missing with {}, `sqs: ` in yaml parses a literal `None`
             if service is None:
-                service = {}
-            # Make a copy of the dict
-            services[name] = [*service.keys()]
+                service = set()
+            if isinstance(service, dict):
+                service = set(service.keys())
+            if isinstance(service, set):
+                # Make a copy of the set for ourselves
+                service = set(service)
+            services[name] = set(service)
     return services
 
 
diff --git a/aws_doc_sdk_examples_tools/metadata_errors.py b/aws_doc_sdk_examples_tools/metadata_errors.py
index 982fb76..9a40f6e 100644
--- a/aws_doc_sdk_examples_tools/metadata_errors.py
+++ b/aws_doc_sdk_examples_tools/metadata_errors.py
@@ -101,6 +101,9 @@ def __str__(self) -> str:
         errs = "\n".join([f"\t{err}" for err in self._errors])
         return f"ExampleErrors with {len(self)} errors:\n{errs}"
 
+    def __eq__(self, __value: object) -> bool:
+        return isinstance(__value, MetadataErrors) and self._errors == __value._errors
+
 
 @dataclass
 class MissingServiceBody(MetadataParseError):
diff --git a/aws_doc_sdk_examples_tools/metadata_test.py b/aws_doc_sdk_examples_tools/metadata_test.py
index dd70219..b31f190 100644
--- a/aws_doc_sdk_examples_tools/metadata_test.py
+++ b/aws_doc_sdk_examples_tools/metadata_test.py
@@ -10,8 +10,9 @@
 from pathlib import Path
 from typing import List, Set, Tuple
 
-from aws_doc_sdk_examples_tools import metadata_errors
-from aws_doc_sdk_examples_tools.metadata import (
+from . import metadata_errors
+from .metadata_errors import MetadataErrors
+from .metadata import (
     parse,
     Example,
     Url,
@@ -20,9 +21,9 @@
     Excerpt,
     idFormat,
 )
-from aws_doc_sdk_examples_tools.doc_gen import DocGen
-from aws_doc_sdk_examples_tools.sdks import Sdk
-from aws_doc_sdk_examples_tools.services import Service, ServiceExpanded
+from .doc_gen import DocGen
+from .sdks import Sdk
+from .services import Service, ServiceExpanded
 
 
 def load(
@@ -144,9 +145,9 @@ def test_parse():
         title_abbrev="Deleting a topic",
         synopsis="Shows how to delete an &SNS; topic.",
         services={
-            "sns": ["Operation1", "Operation2"],
-            "ses": ["Operation1", "Operation2"],
-            "sqs": [],
+            "sns": set(["Operation1", "Operation2"]),
+            "ses": set(["Operation1", "Operation2"]),
+            "sqs": set(),
         },
         languages={"C++": language},
     )
@@ -185,7 +186,7 @@ def test_parse_cross():
         title="Delete Topic",
         title_abbrev="delete topic",
         synopsis="",
-        services={"sns": []},
+        services={"sns": set()},
         languages={"Java": language},
     )
     assert actual[0] == example
@@ -224,7 +225,7 @@ def test_parse_curated():
         title_abbrev="AutoGluon Tabular with SageMaker Pipelines",
         source_key="amazon-sagemaker-examples",
         languages={"Java": language},
-        services={"s3": []},
+        services={"s3": set()},
         synopsis="use AutoGluon with SageMaker Pipelines.",
     )
 
@@ -257,7 +258,7 @@ def test_verify_load_successful():
                 sdk_version=3,
                 github=None,
                 block_content=None,
-                add_services={"s3": []},
+                add_services={"s3": set()},
                 excerpts=[
                     Excerpt(
                         description="Descriptive",
@@ -312,7 +313,7 @@ def test_verify_load_successful():
         category="Usage",
         service_main=None,
         languages=languages,
-        services={"sns": [], "sqs": []},
+        services={"sns": set(), "sqs": set()},
     )
     assert actual[0] == example
 
@@ -461,5 +462,39 @@ def test_idFormat():
     assert not idFormat("test", TEST_SERVICES)
 
 
+@pytest.mark.parametrize(
+    ["a", "b", "d"],
+    [
+        (
+            DocGen(
+                root=Path("/a"),
+                errors=MetadataErrors(),
+                sdks={
+                    "a": Sdk(name="a", guide="guide_a", property="a_prop", versions=[])
+                },
+            ),
+            DocGen(
+                root=Path("/b"),
+                errors=MetadataErrors(),
+                sdks={
+                    "b": Sdk(name="b", guide="guide_b", property="b_prop", versions=[])
+                },
+            ),
+            DocGen(
+                root=Path("/a"),
+                errors=MetadataErrors(),
+                sdks={
+                    "a": Sdk(name="a", guide="guide_a", property="a_prop", versions=[]),
+                    "b": Sdk(name="b", guide="guide_b", property="b_prop", versions=[]),
+                },
+            ),
+        )
+    ],
+)
+def test_merge(a: DocGen, b: DocGen, d: DocGen):
+    a.merge(b)
+    assert a == d
+
+
 if __name__ == "__main__":
     pytest.main([__file__, "-vv"])
diff --git a/aws_doc_sdk_examples_tools/metadata_validator.py b/aws_doc_sdk_examples_tools/metadata_validator.py
index 232520d..ac0598f 100755
--- a/aws_doc_sdk_examples_tools/metadata_validator.py
+++ b/aws_doc_sdk_examples_tools/metadata_validator.py
@@ -21,7 +21,7 @@
 from yamale import YamaleError  # type: ignore
 from yamale.validators import DefaultValidators, Validator, String  # type: ignore
 
-from aws_doc_sdk_examples_tools.metadata_errors import (
+from .metadata_errors import (
     MetadataErrors,
     MetadataParseError,
 )
@@ -185,12 +185,11 @@ def validate_files(
 
 
 def validate_metadata(doc_gen_root: Path, errors: MetadataErrors) -> MetadataErrors:
-    with open(Path(__file__).parent.parent / "config" / "sdks.yaml") as sdks_file:
+    config = Path(__file__).parent / "config"
+    with open(config / "sdks.yaml") as sdks_file:
         sdks_yaml: Dict[str, Any] = yaml.safe_load(sdks_file)
 
-    with open(
-        Path(__file__).parent.parent / "config" / "services.yaml"
-    ) as services_file:
+    with open(config / "services.yaml") as services_file:
         services_yaml = yaml.safe_load(services_file)
 
     SdkVersion.sdks = sdks_yaml
@@ -207,7 +206,7 @@ def validate_metadata(doc_gen_root: Path, errors: MetadataErrors) -> MetadataErr
     validators[BlockContent.tag] = BlockContent
     validators[String.tag] = StringExtension
 
-    schema_root = Path(__file__).parent.parent / "config"
+    schema_root = Path(__file__).parent / "config"
 
     to_validate = [
         # (schema, metadata_glob)
diff --git a/aws_doc_sdk_examples_tools/project_validator.py b/aws_doc_sdk_examples_tools/project_validator.py
index 994be35..9c6a315 100644
--- a/aws_doc_sdk_examples_tools/project_validator.py
+++ b/aws_doc_sdk_examples_tools/project_validator.py
@@ -27,14 +27,14 @@
 from pathlib import Path
 from typing import List
 
-from aws_doc_sdk_examples_tools.file_utils import get_files
-from aws_doc_sdk_examples_tools.metadata_errors import (
+from .file_utils import get_files
+from .metadata_errors import (
     MetadataErrors,
     MetadataError,
     MetadataParseError,
     DuplicateItemException,
 )
-from aws_doc_sdk_examples_tools.spdx import verify_spdx
+from .spdx import verify_spdx
 from aws_doc_sdk_examples_tools import validator_config
 
 logger = logging.getLogger(__name__)
@@ -58,7 +58,6 @@ def check_files(root: Path, errors: MetadataErrors, do_check_spdx: bool):
 
         verify_no_deny_list_words(file_contents, file_path, errors)
         verify_no_secret_keys(file_contents, file_path, errors)
-        verify_no_secret_keys(file_contents, file_path, errors)
         if do_check_spdx:
             verify_spdx(file_contents, file_path, errors)
 
diff --git a/aws_doc_sdk_examples_tools/project_validator_test.py b/aws_doc_sdk_examples_tools/project_validator_test.py
index a42e490..7b30987 100644
--- a/aws_doc_sdk_examples_tools/project_validator_test.py
+++ b/aws_doc_sdk_examples_tools/project_validator_test.py
@@ -10,7 +10,7 @@
 from typing import List
 
 from aws_doc_sdk_examples_tools import project_validator
-from aws_doc_sdk_examples_tools.metadata_errors import MetadataErrors
+from .metadata_errors import MetadataErrors
 
 
 @pytest.mark.parametrize(
diff --git a/aws_doc_sdk_examples_tools/py.typed b/aws_doc_sdk_examples_tools/py.typed
new file mode 100644
index 0000000..e69de29
diff --git a/aws_doc_sdk_examples_tools/sdks.py b/aws_doc_sdk_examples_tools/sdks.py
index 2618f82..66867a9 100644
--- a/aws_doc_sdk_examples_tools/sdks.py
+++ b/aws_doc_sdk_examples_tools/sdks.py
@@ -7,7 +7,7 @@
 from dataclasses import dataclass, field
 
 from aws_doc_sdk_examples_tools import metadata_errors
-from aws_doc_sdk_examples_tools.metadata_errors import (
+from .metadata_errors import (
     MetadataErrors,
     MetadataParseError,
     check_mapping,
@@ -123,6 +123,12 @@ def from_yaml(
         )
 
 
+@dataclass
+class SdkWithNoVersionsError(metadata_errors.MetadataError):
+    def message(self):
+        return "SDK has no versions"
+
+
 @dataclass
 class Sdk:
     name: str
@@ -130,6 +136,10 @@ class Sdk:
     guide: str
     property: str
 
+    def validate(self, errors: MetadataErrors):
+        if len(self.versions) == 0:
+            errors.append(SdkWithNoVersionsError(id=self.name))
+
     @classmethod
     def from_yaml(cls, name: str, yaml: Dict[str, Any]) -> tuple[Sdk, MetadataErrors]:
         errors = MetadataErrors()
diff --git a/aws_doc_sdk_examples_tools/sdks_test.py b/aws_doc_sdk_examples_tools/sdks_test.py
index ae76464..4717c32 100644
--- a/aws_doc_sdk_examples_tools/sdks_test.py
+++ b/aws_doc_sdk_examples_tools/sdks_test.py
@@ -11,7 +11,7 @@
 from typing import Dict, Tuple
 
 from aws_doc_sdk_examples_tools import metadata_errors
-from aws_doc_sdk_examples_tools.sdks import (
+from .sdks import (
     parse,
     Sdk,
     SdkVersion,
diff --git a/aws_doc_sdk_examples_tools/services.py b/aws_doc_sdk_examples_tools/services.py
index d82d460..77f880d 100644
--- a/aws_doc_sdk_examples_tools/services.py
+++ b/aws_doc_sdk_examples_tools/services.py
@@ -6,7 +6,7 @@
 from typing import Any, Dict, Optional, Set, Union
 from dataclasses import dataclass, field
 from aws_doc_sdk_examples_tools import metadata_errors
-from aws_doc_sdk_examples_tools.metadata_errors import MetadataErrors, check_mapping
+from .metadata_errors import MetadataErrors, check_mapping
 
 
 @dataclass
@@ -35,6 +35,9 @@ class Service:
     guide: Optional[ServiceGuide] = field(default=None)
     tags: Dict[str, Set[str]] = field(default_factory=dict)
 
+    def validate(self, errors: MetadataErrors):
+        pass
+
     @classmethod
     def from_yaml(
         cls, name: str, yaml: Dict[str, Any]
diff --git a/aws_doc_sdk_examples_tools/services_test.py b/aws_doc_sdk_examples_tools/services_test.py
index 47f7173..0080125 100644
--- a/aws_doc_sdk_examples_tools/services_test.py
+++ b/aws_doc_sdk_examples_tools/services_test.py
@@ -7,7 +7,7 @@
 import yaml
 
 from aws_doc_sdk_examples_tools import metadata_errors
-from aws_doc_sdk_examples_tools.services import (
+from .services import (
     parse,
     Service,
     ServiceGuide,
diff --git a/aws_doc_sdk_examples_tools/snippets.py b/aws_doc_sdk_examples_tools/snippets.py
index 27e9a91..7236264 100644
--- a/aws_doc_sdk_examples_tools/snippets.py
+++ b/aws_doc_sdk_examples_tools/snippets.py
@@ -9,9 +9,9 @@
 
 from aws_doc_sdk_examples_tools import validator_config
 
-from aws_doc_sdk_examples_tools.file_utils import get_files, clear
-from aws_doc_sdk_examples_tools.metadata import Example
-from aws_doc_sdk_examples_tools.metadata_errors import MetadataErrors, MetadataError
+from .file_utils import get_files, clear
+from .metadata import Example
+from .metadata_errors import MetadataErrors, MetadataError
 
 SNIPPET_START = "snippet-start:["
 SNIPPET_END = "snippet-end:["
@@ -81,21 +81,21 @@ def message(self):
         return f" unicode error: {str(self.err)}"
 
 
-def _tag_from_line(token: str, line: str) -> str:
+def _tag_from_line(token: str, line: str, prefix: str) -> str:
     tag_start = line.find(token) + len(token)
     tag_end = line.find("]", tag_start)
-    return line[tag_start:tag_end].strip()
+    return prefix + line[tag_start:tag_end].strip()
 
 
 def parse_snippets(
-    lines: List[str], file: Path
+    lines: List[str], file: Path, prefix: str
 ) -> Tuple[Dict[str, Snippet], MetadataErrors]:
     snippets: Dict[str, Snippet] = {}
     errors = MetadataErrors()
     open_tags: Set[str] = set()
     for line_idx, line in enumerate(lines):
         if SNIPPET_START in line:
-            tag = _tag_from_line(SNIPPET_START, line)
+            tag = _tag_from_line(SNIPPET_START, line, prefix)
             if tag in snippets:
                 errors.append(
                     DuplicateSnippetStartError(file=str(file), line=line_idx, tag=tag)
@@ -110,7 +110,7 @@ def parse_snippets(
                 )
                 open_tags.add(tag)
         elif SNIPPET_END in line:
-            tag = _tag_from_line(SNIPPET_END, line)
+            tag = _tag_from_line(SNIPPET_END, line, prefix)
             if tag not in snippets:
                 errors.append(
                     MissingSnippetStartError(file=str(file), line=line_idx, tag=tag)
@@ -135,23 +135,25 @@ def parse_snippets(
     return snippets, errors
 
 
-def find_snippets(file: Path) -> Tuple[Dict[str, Snippet], MetadataErrors]:
+def find_snippets(file: Path, prefix: str) -> Tuple[Dict[str, Snippet], MetadataErrors]:
     errors = MetadataErrors()
     snippets: Dict[str, Snippet] = {}
     with open(file, encoding="utf-8") as snippet_file:
         try:
-            snippets, errs = parse_snippets(snippet_file.readlines(), file)
+            snippets, errs = parse_snippets(snippet_file.readlines(), file, prefix)
             errors.extend(errs)
         except UnicodeDecodeError as err:
             errors.append(MetadataUnicodeError(file=str(file), err=err))
     return snippets, errors
 
 
-def collect_snippets(root: Path) -> Tuple[Dict[str, Snippet], MetadataErrors]:
+def collect_snippets(
+    root: Path, prefix: str = ""
+) -> Tuple[Dict[str, Snippet], MetadataErrors]:
     snippets: Dict[str, Snippet] = {}
     errors = MetadataErrors()
     for file in get_files(root, validator_config.skip):
-        snips, errs = find_snippets(file)
+        snips, errs = find_snippets(file, prefix)
         snippets.update(snips)
         errors.extend(errs)
     return snippets, errors
@@ -207,32 +209,31 @@ def validate_snippets(
                                     tag=snippet_tag,
                                 )
                             )
-                    for snippet_file in excerpt.snippet_files:
-                        if not (root / snippet_file).exists():
-                            # Ensure all snippet_files exist
-                            errors.append(
-                                MissingSnippetFile(
-                                    file=example.file,
-                                    snippet_file=snippet_file,
-                                    id=f"{lang}:{version.sdk_version}",
-                                )
-                            )
-                        if re.search(win_unsafe_re, str(snippet_file)):
-                            errors.append(
-                                WindowsUnsafeSnippetFile(
-                                    file=example.file,
-                                    snippet_file=snippet_file,
-                                    id=f"{lang}:{version.sdk_version}",
-                                )
-                            )
-                        snippet_files.add(snippet_file)
+    for snippet_file in excerpt.snippet_files:
+        if not (root / snippet_file).exists():
+            # Ensure all snippet_files exist
+            errors.append(
+                MissingSnippetFile(
+                    file=example.file,
+                    snippet_file=snippet_file,
+                    id=f"{lang}:{version.sdk_version}",
+                )
+            )
+        if re.search(win_unsafe_re, str(snippet_file)):
+            errors.append(
+                WindowsUnsafeSnippetFile(
+                    file=example.file,
+                    snippet_file=snippet_file,
+                    id=f"{lang}:{version.sdk_version}",
+                )
+            )
 
 
-def write_snippets(root: Path, snippets: Dict[str, Snippet]):
+def write_snippets(root: Path, snippets: Dict[str, Snippet], check: bool = False):
     errors = MetadataErrors()
     for tag in snippets:
         name = root / f"{tag}.txt"
-        if name.exists():
+        if check and name.exists():
             errors.append(SnippetAlreadyWritten(file=str(name)))
         else:
             try:
@@ -246,8 +247,7 @@ def write_snippets(root: Path, snippets: Dict[str, Snippet]):
 def write_snippet_file(folder: Path, snippet_file: Path):
     name = str(snippet_file).replace("/", ".")
     dest = folder / f"{name}.txt"
-    if not dest.exists():
-        copyfile(folder / snippet_file, dest)
+    copyfile(folder / snippet_file, dest)
 
 
 def main():
diff --git a/aws_doc_sdk_examples_tools/snippets_test.py b/aws_doc_sdk_examples_tools/snippets_test.py
index 79c242b..178ffb9 100644
--- a/aws_doc_sdk_examples_tools/snippets_test.py
+++ b/aws_doc_sdk_examples_tools/snippets_test.py
@@ -62,6 +62,6 @@
 def test_verify_snippet_start_end(file_contents: str, expected_error_count: int):
     """Test that various kinds of mismatched snippet-start and -end tags are
     counted correctly as errors."""
-    _, errors = snippets.parse_snippets(file_contents.split("\n"), Path("test"))
+    _, errors = snippets.parse_snippets(file_contents.split("\n"), Path("test"), "")
     error_count = len(errors)
     assert error_count == expected_error_count
diff --git a/aws_doc_sdk_examples_tools/spdx.py b/aws_doc_sdk_examples_tools/spdx.py
index 7c36e34..1532c73 100644
--- a/aws_doc_sdk_examples_tools/spdx.py
+++ b/aws_doc_sdk_examples_tools/spdx.py
@@ -8,7 +8,7 @@
 import re
 from sys import argv
 
-from aws_doc_sdk_examples_tools.metadata_errors import MetadataError, MetadataErrors
+from .metadata_errors import MetadataError, MetadataErrors
 from aws_doc_sdk_examples_tools import validator_config
 
 
@@ -49,6 +49,8 @@ def verify_spdx(file_contents: str, file_location: Path, errors: MetadataErrors)
     if file_location.suffix in validator_config.IGNORE_SPDX_SUFFIXES:
         return
     lines = file_contents.splitlines()
+    if len(lines) == 0:
+        return
     if skip_first_line(lines):
         lines = lines[1:]
     if len(lines) < 2:
diff --git a/aws_doc_sdk_examples_tools/validate.py b/aws_doc_sdk_examples_tools/validate.py
index fe28ad8..54b132c 100755
--- a/aws_doc_sdk_examples_tools/validate.py
+++ b/aws_doc_sdk_examples_tools/validate.py
@@ -5,7 +5,7 @@
 from pathlib import Path
 from sys import exit
 
-from aws_doc_sdk_examples_tools.doc_gen import DocGen
+from .doc_gen import DocGen
 
 
 def main():
diff --git a/setup.py b/setup.py
index 382fe9f..fd8196e 100644
--- a/setup.py
+++ b/setup.py
@@ -7,6 +7,7 @@
     name="aws_doc_sdk_examples_tools",
     version="0.0.1",
     packages=["aws_doc_sdk_examples_tools"],
+    package_data={"aws_doc_sdk_examples_tools": ["config/*.yaml"]},
     install_requires=[
         "pathspec==0.11.2",
         "PyYAML==6.0.1",