diff --git a/datafields.ttl b/datafields.ttl
index 0968706..5d3f3de 100644
--- a/datafields.ttl
+++ b/datafields.ttl
@@ -18,6 +18,7 @@ ff:FirstNamesShape a sh:NodeShape ;
     sh:property [
         sh:path ff:hasFirstNames ;
         sh:datatype xsd:string ;
+        sh:maxCount 1 ;
     ] .
 
 ff:hasFamilyName a ff:FimDataFieldProperty, ff:DataField ;
@@ -33,6 +34,7 @@ ff:FamilyNameShape a sh:NodeShape ;
     sh:property [
           sh:path ff:hasFamilyName ;
           sh:datatype xsd:string ;
+          sh:maxCount 1 ;
       ] .
 
 ff:hasBirthday a ff:FimDataFieldProperty, ff:DataField ;
@@ -48,6 +50,7 @@ ff:BirthdayShape a sh:NodeShape ;
     sh:property [
         sh:path ff:hasBirthday ;
         sh:datatype xsd:date ;
+        sh:maxCount 1 ;
     ] .
 
 ff:hasGender a ff:FimDataFieldProperty, ff:DataField ;
@@ -62,6 +65,7 @@ ff:GenderShape a sh:NodeShape ;
     sh:property [
         sh:path ff:hasGender ;
         sh:in ("weiblich" "männlich" "divers" "keine Angabe") ;
+        sh:maxCount 1 ;
         rdfs:seeAlso <https://schema.fim.fitko.net/fields/baukasten/F60000332/1.3>
     ] .
 
@@ -77,6 +81,7 @@ ff:BirthPlaceShape a sh:NodeShape ;
     sh:property [
          sh:path ff:hasBirthPlace ;
          sh:datatype xsd:string ;
+         sh:maxCount 1 ;
      ] .
 
 ff:hasResidence a ff:FimDataFieldProperty, ff:DataField ;
@@ -91,6 +96,7 @@ ff:ResidenceShape a sh:NodeShape ;
     sh:property [
         sh:path ff:hasResidence ;
         sh:datatype xsd:string ;
+        sh:maxCount 1 ;
     ] .
 
 ff:hasMaritalStatus a ff:FimDataFieldProperty, ff:DataField ;
@@ -104,6 +110,7 @@ ff:MaritalStatusShape a sh:NodeShape ;
     sh:property [
         sh:path ff:hasMaritalStatus ;
         sh:in ("LD" "VH" "VW" "GS" "EA" "LP" "LV" "LA" "LE" "NB") ;
+        sh:maxCount 1 ;
         ff:shInAbbrevationsStandFor ("ledig" "verheiratet" "verwitwet" "geschieden" "Ehe aufgehoben" "in eingetragener Lebenspartnerschaft" "durch Tod aufgelöste Lebenspartnerschaft" "aufgehobene Lebenspartnerschaft" "durch Todeserklärung aufgelöste Lebenspartnerschaft" "nicht bekannt") ;
         rdfs:seeAlso <https://www.xrepository.de/details/urn:de:dsmeld:schluesseltabelle:familienstand>
     ] .
@@ -141,6 +148,7 @@ ff:AgeShape a sh:NodeShape ;
         sh:path ff:hasAge ;
         sh:datatype xsd:integer ;
         sh:minInclusive 0 ;
+        sh:maxCount 1 ;
     ] .
 
 ff:paysRentCold a ff:FimDataFieldProperty, ff:DataField ;
@@ -168,6 +176,7 @@ ff:hasLivingAreaShape a sh:NodeShape ;
         sh:path ff:hasLivingArea ;
         sh:datatype xsd:integer ;
         sh:minInclusive 0 ;
+        sh:maxCount 1 ;
     ] .
 
 ff:hasNumberOfChildren a ff:FimDataFieldProperty, ff:DataField ;
@@ -175,6 +184,14 @@ ff:hasNumberOfChildren a ff:FimDataFieldProperty, ff:DataField ;
     ff:hasFimVersion "1.0" ;
     rdfs:label "Anzahl Kinder" ;
     rdfs:comment "Angabe der Anzahl der im Haushalt lebenden Kinder." .
+ff:hasNumberOfChildrenShape a sh:NodeShape ;
+    sh:targetClass ff:Citizen ;
+    sh:property [
+        sh:path ff:hasNumberOfChildren ;
+        sh:datatype xsd:integer ;
+        sh:minInclusive 0 ;
+        sh:maxCount 1 ;
+    ] .
 
 ff:hasIncomeBrutto a ff:FimDataFieldProperty, ff:DataField ;
     ff:hasFimId fim:F00000575 ;
@@ -187,6 +204,7 @@ ff:hasIncomeBruttoShape a sh:NodeShape ;
         sh:path ff:hasIncomeBrutto ;
         sh:datatype xsd:integer ;
         sh:minInclusive 0 ;
+        sh:maxCount 1 ;
     ] .
 
 ff:hasIncomeNetto a ff:FimDataFieldProperty, ff:DataField ;
@@ -200,6 +218,7 @@ ff:hasIncomeNettoShape a sh:NodeShape ;
         sh:path ff:hasIncomeNetto ;
         sh:datatype xsd:integer ;
         sh:minInclusive 0 ;
+        sh:maxCount 1 ;
     ] .
 
 ff:receivesKindergeld a ff:FimLeistung, ff:DataField ;
@@ -228,6 +247,7 @@ ff:receivesWohngeldShape a sh:NodeShape ;
         sh:path ff:receivesWohngeld ;
         sh:datatype xsd:integer ;
         sh:minInclusive 0 ;
+        sh:maxCount 1 ;
    ] .
 
 ff:hasChild a ff:DataField ;