diff --git a/src/openklant/components/klantinteracties/api/serializers/partijen.py b/src/openklant/components/klantinteracties/api/serializers/partijen.py
index f12797a5..6fce8f87 100644
--- a/src/openklant/components/klantinteracties/api/serializers/partijen.py
+++ b/src/openklant/components/klantinteracties/api/serializers/partijen.py
@@ -444,7 +444,7 @@ def validate(self, attrs):
 
         return super().validate(attrs)
 
-    def assert_partij(self, partij):
+    def validate_partij(self, partij):
         if not partij:
             raise serializers.ValidationError(
                 {"identificeerdePartij": _("Dit veld is vereist.")},
@@ -454,13 +454,13 @@ def assert_partij(self, partij):
     @handle_db_exceptions
     @transaction.atomic
     def update(self, instance, validated_data):
-        self.assert_partij(validated_data["partij"])
+        self.validate_partij(validated_data["partij"])
         return super().update(instance, validated_data)
 
     @handle_db_exceptions
     @transaction.atomic
     def create(self, validated_data):
-        self.assert_partij(validated_data["partij"])
+        self.validate_partij(validated_data["partij"])
         return super().create(validated_data)
 
 
@@ -634,6 +634,11 @@ def validate_partij_identificatoren(self, attrs):
         return attrs
 
     def update_or_create_partij_identificator(self, partij_identificator):
+        sub_identificator_van = partij_identificator["sub_identificator_van"]
+        if isinstance(sub_identificator_van, PartijIdentificator):
+            partij_identificator["sub_identificator_van"] = {
+                "uuid": sub_identificator_van.uuid
+            }
         partij_identificator_serializer = PartijIdentificatorSerializer(
             data=partij_identificator
         )
diff --git a/src/openklant/components/klantinteracties/api/tests/test_partijen.py b/src/openklant/components/klantinteracties/api/tests/test_partijen.py
index 37f87b1e..3bb5340e 100644
--- a/src/openklant/components/klantinteracties/api/tests/test_partijen.py
+++ b/src/openklant/components/klantinteracties/api/tests/test_partijen.py
@@ -2503,6 +2503,260 @@ def test_invalid_create_where_partij_is_selected(self):
 
         self.assertEqual(Partij.objects.all().count(), 1)
 
+    def test_partially_update_with_null_values(self):
+        partij = PartijFactory.create(
+            nummer="1298329191",
+            interne_notitie="interneNotitie",
+            voorkeurs_digitaal_adres=None,
+            voorkeurs_rekeningnummer=None,
+            indicatie_geheimhouding=True,
+            voorkeurstaal="ndl",
+            indicatie_actief=True,
+            soort_partij="persoon",
+        )
+
+        detail_url = reverse(
+            "klantinteracties:partij-detail", kwargs={"uuid": str(partij.uuid)}
+        )
+
+        with self.subTest("partij_identificatoren_not_specified"):
+            data = {"soortPartij": "organisatie"}
+            self.assertEqual(partij.soort_partij, "persoon")
+            self.assertEqual(partij.partijidentificator_set.count(), 0)
+            response = self.client.patch(detail_url, data)
+            response_data = response.json()
+            self.assertEqual(response.status_code, status.HTTP_200_OK)
+            self.assertEqual(response_data["partijIdentificatoren"], [])
+            self.assertEqual(response_data["soortPartij"], "organisatie")
+            self.assertEqual(partij.partijidentificator_set.count(), 0)
+
+            BsnPartijIdentificatorFactory.create(
+                partij=partij, partij_identificator_object_id="296648875"
+            )
+            # Resend update request
+            # No changes to the partij_identificator because the value wasn't specified in PATCH
+            self.assertEqual(partij.partijidentificator_set.count(), 1)
+            response = self.client.patch(detail_url, data)
+            response_data = response.json()
+            self.assertEqual(response.status_code, status.HTTP_200_OK)
+
+            partij = Partij.objects.get(uuid=partij.uuid)
+            self.assertEqual(partij.partijidentificator_set.count(), 1)
+            self.assertEqual(len(response_data["partijIdentificatoren"]), 1)
+            self.assertEqual(response_data["soortPartij"], "organisatie")
+            self.assertEqual(partij.soort_partij, "organisatie")
+
+        with self.subTest("partij_identificatoren_null_value"):
+            data = {
+                "soortPartij": "persoon",
+                "partijIdentificatoren": None,
+            }
+            self.assertEqual(partij.soort_partij, "organisatie")
+            self.assertEqual(partij.partijidentificator_set.count(), 1)
+
+            # No changes to the partij_identificator because the value was None in PATCH
+            self.assertEqual(partij.partijidentificator_set.count(), 1)
+            response = self.client.patch(detail_url, data)
+            response_data = response.json()
+            self.assertEqual(response.status_code, status.HTTP_200_OK)
+
+            partij = Partij.objects.get(uuid=partij.uuid)
+            self.assertEqual(partij.partijidentificator_set.count(), 1)
+            self.assertEqual(len(response_data["partijIdentificatoren"]), 1)
+            self.assertEqual(response_data["soortPartij"], "persoon")
+            self.assertEqual(partij.soort_partij, "persoon")
+
+        with self.subTest("partij_identificatoren_empty_list_value"):
+            data = {
+                "soortPartij": "organisatie",
+                "partijIdentificatoren": [],
+            }
+            self.assertEqual(partij.soort_partij, "persoon")
+            self.assertEqual(partij.partijidentificator_set.count(), 1)
+
+            # Delete all partij_identificatoren because the value was [] in PATCH
+            response = self.client.patch(detail_url, data)
+            response_data = response.json()
+            self.assertEqual(response.status_code, status.HTTP_200_OK)
+            partij = Partij.objects.get(uuid=partij.uuid)
+            self.assertEqual(partij.partijidentificator_set.count(), 0)
+            self.assertEqual(len(response_data["partijIdentificatoren"]), 0)
+            self.assertEqual(response_data["soortPartij"], "organisatie")
+            self.assertEqual(partij.soort_partij, "organisatie")
+
+    def test_partially_update_where_all_partij_identificatoren_have_uuid(self):
+        partij = PartijFactory.create(
+            nummer="1298329191",
+            interne_notitie="interneNotitie",
+            voorkeurs_digitaal_adres=None,
+            voorkeurs_rekeningnummer=None,
+            soort_partij="persoon",
+            indicatie_geheimhouding=True,
+            voorkeurstaal="ndl",
+            indicatie_actief=True,
+        )
+        detail_url = reverse(
+            "klantinteracties:partij-detail", kwargs={"uuid": str(partij.uuid)}
+        )
+        bsn = BsnPartijIdentificatorFactory.create(
+            partij=partij, partij_identificator_object_id="296648875"
+        )
+        kvk_nummer = KvkNummerPartijIdentificatorFactory.create(
+            partij=partij, partij_identificator_object_id="12345678"
+        )
+        vestigingsnummer = VestigingsnummerPartijIdentificatorFactory.create(
+            partij=partij, partij_identificator_object_id="111122223333"
+        )
+
+        # changes are only for objectId
+        data = {
+            "soortPartij": "organisatie",
+            "partijIdentificatoren": [
+                {
+                    "uuid": str(bsn.uuid),
+                    "partijIdentificator": {
+                        "codeObjecttype": "natuurlijk_persoon",
+                        "codeSoortObjectId": "bsn",
+                        "objectId": "123456782",
+                        "codeRegister": "brp",
+                    },
+                },
+                {
+                    "uuid": str(kvk_nummer.uuid),
+                    "partijIdentificator": {
+                        "codeObjecttype": "niet_natuurlijk_persoon",
+                        "codeSoortObjectId": "kvk_nummer",
+                        "objectId": "11112222",
+                        "codeRegister": "hr",
+                    },
+                },
+                {
+                    "uuid": str(vestigingsnummer.uuid),
+                    "sub_identificator_van": {"uuid": str(kvk_nummer.uuid)},
+                    "partijIdentificator": {
+                        "codeObjecttype": "vestiging",
+                        "codeSoortObjectId": "vestigingsnummer",
+                        "objectId": "444455556666",
+                        "codeRegister": "hr",
+                    },
+                },
+            ],
+        }
+        response = self.client.patch(detail_url, data)
+        response_data = response.json()
+
+        self.assertEqual(response.status_code, status.HTTP_200_OK)
+        partij = Partij.objects.get(pk=partij.pk)
+
+        self.assertEqual(len(response_data["partijIdentificatoren"]), 3)
+        self.assertEqual(response_data["soortPartij"], "organisatie")
+        self.assertEqual(partij.soort_partij, "organisatie")
+        new_bsn = partij.partijidentificator_set.get(
+            partij_identificator_code_soort_object_id="bsn"
+        )
+        new_kvk_nummer = partij.partijidentificator_set.get(
+            partij_identificator_code_soort_object_id="kvk_nummer"
+        )
+        new_vestigingsnummer = partij.partijidentificator_set.get(
+            partij_identificator_code_soort_object_id="vestigingsnummer"
+        )
+        # assert that they are the same objects
+        self.assertEqual(new_bsn.uuid, bsn.uuid)
+        self.assertEqual(new_kvk_nummer.uuid, kvk_nummer.uuid)
+        self.assertEqual(new_vestigingsnummer.uuid, vestigingsnummer.uuid)
+        # assert that the object_ids have been updated
+        self.assertEqual(new_bsn.partij_identificator_object_id, "123456782")
+        self.assertEqual(new_kvk_nummer.partij_identificator_object_id, "11112222")
+        self.assertEqual(
+            new_vestigingsnummer.partij_identificator_object_id, "444455556666"
+        )
+
+    def test_partially_update_where_not_all_partij_identificatoren_have_uuid(self):
+        partij = PartijFactory.create(
+            nummer="1298329191",
+            interne_notitie="interneNotitie",
+            voorkeurs_digitaal_adres=None,
+            voorkeurs_rekeningnummer=None,
+            soort_partij="persoon",
+            indicatie_geheimhouding=True,
+            voorkeurstaal="ndl",
+            indicatie_actief=True,
+        )
+        detail_url = reverse(
+            "klantinteracties:partij-detail", kwargs={"uuid": str(partij.uuid)}
+        )
+        bsn = BsnPartijIdentificatorFactory.create(
+            partij=partij, partij_identificator_object_id="296648875"
+        )
+        kvk_nummer = KvkNummerPartijIdentificatorFactory.create(
+            partij=partij, partij_identificator_object_id="12345678"
+        )
+        vestigingsnummer = VestigingsnummerPartijIdentificatorFactory.create(
+            partij=partij, partij_identificator_object_id="111122223333"
+        )
+
+        # changes are only for objectId
+        data = {
+            "soortPartij": "organisatie",
+            "partijIdentificatoren": [
+                {
+                    "partijIdentificator": {
+                        "codeObjecttype": "natuurlijk_persoon",
+                        "codeSoortObjectId": "bsn",
+                        "objectId": "123456782",
+                        "codeRegister": "brp",
+                    },
+                },
+                {
+                    "uuid": str(kvk_nummer.uuid),
+                    "partijIdentificator": {
+                        "codeObjecttype": "niet_natuurlijk_persoon",
+                        "codeSoortObjectId": "kvk_nummer",
+                        "objectId": "11112222",
+                        "codeRegister": "hr",
+                    },
+                },
+                {
+                    "uuid": str(vestigingsnummer.uuid),
+                    "sub_identificator_van": {"uuid": str(kvk_nummer.uuid)},
+                    "partijIdentificator": {
+                        "codeObjecttype": "vestiging",
+                        "codeSoortObjectId": "vestigingsnummer",
+                        "objectId": "444455556666",
+                        "codeRegister": "hr",
+                    },
+                },
+            ],
+        }
+        response = self.client.patch(detail_url, data)
+        response_data = response.json()
+
+        self.assertEqual(response.status_code, status.HTTP_200_OK)
+        partij = Partij.objects.get(pk=partij.pk)
+        self.assertEqual(len(response_data["partijIdentificatoren"]), 3)
+        self.assertEqual(response_data["soortPartij"], "organisatie")
+        self.assertEqual(partij.soort_partij, "organisatie")
+        new_bsn = partij.partijidentificator_set.get(
+            partij_identificator_code_soort_object_id="bsn"
+        )
+        new_kvk_nummer = partij.partijidentificator_set.get(
+            partij_identificator_code_soort_object_id="kvk_nummer"
+        )
+        new_vestigingsnummer = partij.partijidentificator_set.get(
+            partij_identificator_code_soort_object_id="vestigingsnummer"
+        )
+        # assert bsn was deleted and then created again with new values
+        self.assertNotEqual(new_bsn.uuid, bsn.uuid)
+        # assert that they are the same objects
+        self.assertEqual(new_kvk_nummer.uuid, kvk_nummer.uuid)
+        self.assertEqual(new_vestigingsnummer.uuid, vestigingsnummer.uuid)
+        # assert that the object_ids have been updated
+        self.assertEqual(new_bsn.partij_identificator_object_id, "123456782")
+        self.assertEqual(new_kvk_nummer.partij_identificator_object_id, "11112222")
+        self.assertEqual(
+            new_vestigingsnummer.partij_identificator_object_id, "444455556666"
+        )
+
 
 class PartijIdentificatorTests(APITestCase):
     def test_list_partij_identificator(self):
@@ -2576,6 +2830,7 @@ def test_update_partij_identificator(self):
         partij, partij2 = PartijFactory.create_batch(2)
         partij_identificator = BsnPartijIdentificatorFactory.create(
             partij=partij,
+            andere_partij_identificator="anderePartijIdentificator",
             partij_identificator_object_id="296648875",
         )
 
@@ -2916,7 +3171,7 @@ def test_invalid_create_partij_required(self):
     def test_invalid_create_duplicate_code_soort_object_id_for_partij(self):
         BsnPartijIdentificatorFactory.create(
             partij=self.partij,
-            partij_identificator_object_id="296648875",
+            partij_identificator_object_id="123456782",
         )
 
         data = {
diff --git a/src/openklant/components/klantinteracties/openapi.yaml b/src/openklant/components/klantinteracties/openapi.yaml
index c081ca45..56aa7ff3 100644
--- a/src/openklant/components/klantinteracties/openapi.yaml
+++ b/src/openklant/components/klantinteracties/openapi.yaml
@@ -3065,8 +3065,8 @@ components:
         partijIdentificatoren:
           type: array
           items:
-            $ref: '#/components/schemas/PartijIdentificatorForeignkey'
-          readOnly: true
+            $ref: '#/components/schemas/PartijIdentificator'
+          nullable: true
           description: Partij-identificatoren die hoorde bij deze partij.
         soortPartij:
           allOf:
@@ -3107,7 +3107,6 @@ components:
       - categorieRelaties
       - digitaleAdressen
       - indicatieActief
-      - partijIdentificatoren
       - rekeningnummers
       - soortPartij
       - url
@@ -4836,7 +4835,6 @@ components:
         uuid:
           type: string
           format: uuid
-          readOnly: true
           description: Unieke (technische) identificatiecode van de partij-identificator.
         url:
           type: string
@@ -4871,10 +4869,8 @@ components:
             the child identificator could specify a vestigingsnummer that is unique
             for the KVK number).
       required:
-      - identificeerdePartij
       - partijIdentificator
       - url
-      - uuid
     PartijIdentificatorForeignkey:
       type: object
       properties:
@@ -5391,7 +5387,6 @@ components:
         uuid:
           type: string
           format: uuid
-          readOnly: true
           description: Unieke (technische) identificatiecode van de partij-identificator.
         url:
           type: string