diff --git a/lib/couchdb/document.py b/lib/couchdb/document.py
index 61efdef..373c3c4 100644
--- a/lib/couchdb/document.py
+++ b/lib/couchdb/document.py
@@ -80,9 +80,11 @@ def to_dict(self) -> Dict[str, Any]:
     def add_sample(
         self,
         sample_id: str,
-        lib_prep_option: str,
+        # lib_prep_option: str,
         status: str = "pending",
         flowcell_ids_processed_for: Optional[List[str]] = None,
+        start_time: Optional[str] = None,
+        end_time: Optional[str] = None,
     ) -> None:
         """Adds a new sample to the document.
 
@@ -91,16 +93,38 @@ def add_sample(
             lib_prep_option (str): The library preparation option.
             status (str, optional): The status of the sample. Defaults to "pending".
             flowcell_ids_processed_for (List[str], optional): Flowcell IDs the sample has been processed for.
+            start_time (str, optional): Start time of the sample processing.
+            end_time (str, optional): End time of the sample processing.
         """
-        sample = {
-            "sample_id": sample_id,
-            "status": status,
-            "lib_prep_option": lib_prep_option,
-            "start_time": "",
-            "end_time": "",
-            "flowcell_ids_processed_for": flowcell_ids_processed_for or [],
-        }
-        self.samples.append(sample)
+        existing_sample = self.get_sample(sample_id)
+        if existing_sample:
+            # Update existing sample
+            existing_sample["status"] = status
+            if flowcell_ids_processed_for:
+                existing_sample["flowcell_ids_processed_for"].extend(
+                    flowcell_ids_processed_for
+                )
+                # Remove duplicates
+                existing_sample["flowcell_ids_processed_for"] = list(
+                    set(existing_sample["flowcell_ids_processed_for"])
+                )
+            if start_time:
+                existing_sample["start_time"] = start_time
+            if end_time:
+                existing_sample["end_time"] = end_time
+            # logging.debug(f"Updated sample: {existing_sample}")
+        else:
+            # Add new sample
+            sample = {
+                "sample_id": sample_id,
+                "status": status,
+                # "lib_prep_option": lib_prep_option,
+                "start_time": start_time or "",
+                "end_time": end_time or "",
+                "flowcell_ids_processed_for": flowcell_ids_processed_for or [],
+            }
+            self.samples.append(sample)
+            # logging.debug(f"Added sample: {sample}")
 
     def update_sample_status(self, sample_id: str, status: str) -> None:
         """Updates the status of a specific sample.
@@ -132,7 +156,7 @@ def update_sample_status(self, sample_id: str, status: str) -> None:
         self.check_project_completion()
 
     def get_sample(self, sample_id: str) -> Optional[Dict[str, Any]]:
-        """Retrieves a specific sample by its ID.
+        """Retrieves a specific sample from the samples list by its ID.
 
         Args:
             sample_id (str): The sample ID to retrieve.
diff --git a/lib/couchdb/manager.py b/lib/couchdb/manager.py
index ed24be0..24b95b2 100644
--- a/lib/couchdb/manager.py
+++ b/lib/couchdb/manager.py
@@ -255,6 +255,33 @@ def get_document_by_project_id(self, project_id: str) -> Optional[Dict[str, Any]
             logging.error(f"Error accessing project: {e}")
             return None
 
+    def add_sample(
+        self,
+        project_id: str,
+        sample_id: str,
+        # lib_prep_option: str,
+        status: str = "pending",
+    ) -> None:
+        """Adds a sample to a project and saves the document.
+
+        Args:
+            project_id (str): The project ID.
+            sample_id (str): The sample ID.
+            lib_prep_option (str): The library preparation option.
+            status (str, optional): The status of the sample. Defaults to "pending".
+        """
+        try:
+            document_dict = self.get_document_by_project_id(project_id)
+            if document_dict:
+                ygg_doc = YggdrasilDocument.from_dict(document_dict)
+                ygg_doc.add_sample(sample_id, status)
+                self.save_document(ygg_doc)
+                logging.info(f"Updated project {project_id} with sample.")
+            else:
+                logging.error(f"Project {project_id} does not exist in YggdrasilDB.")
+        except Exception as e:
+            logging.error(f"Error adding sample: {e}")
+
     def update_sample_status(
         self, project_id: str, sample_id: str, status: str
     ) -> None: