diff --git a/apps/authentication/migrations/0050_organization_service_area.py b/apps/authentication/migrations/0050_organization_service_area.py
new file mode 100644
index 0000000..d180777
--- /dev/null
+++ b/apps/authentication/migrations/0050_organization_service_area.py
@@ -0,0 +1,18 @@
+# Generated by Django 5.0 on 2025-12-22 11:59
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('authentication', '0049_alter_bankaccountinformation_account_and_more'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='organization',
+            name='service_area',
+            field=models.ManyToManyField(related_name='service_area', to='authentication.city'),
+        ),
+    ]
diff --git a/apps/herd/web/api/v1/serializers.py b/apps/herd/web/api/v1/serializers.py
index a9fb02f..9efa53a 100644
--- a/apps/herd/web/api/v1/serializers.py
+++ b/apps/herd/web/api/v1/serializers.py
@@ -74,13 +74,32 @@ class RancherOrganizationLinkSerializer(serializers.ModelSerializer):
         rancher = attrs['rancher']
         organization = attrs['organization']
 
-        if self.Meta.model.objects.filter(rancher=rancher, organization=organization).exists():
-            raise HerdException(message="دامدار برای تعاونی مد نظر از قبل وجود دارد", status_code=403)  # noqa
+        if not self.instance:
+            if self.Meta.model.objects.filter(rancher=rancher, organization=organization).exists():
+                raise HerdException(message="دامدار برای تعاونی مد نظر از قبل وجود دارد", status_code=403)  # noqa
+
+            elif self.Meta.model.objects.filter(
+                    rancher=rancher,
+                    organization__parent_organization=organization.parent_organization
+            ).exists():
+                raise HerdException(
+                    message="دامدار نمیتواند زیر مجموعه دو تعاونی با اتحادیه یکسان باشند",  # noqa
+                    status_code=403
+                )
 
         if self.instance:
-            if rancher.city not in organization.service_area:
+            if rancher.city not in organization.service_area.all():
                 raise HerdException(message="دامدار در محدوده فعالیت تعاونی قرار ندارد", status_code=403)  # noqa
 
+            elif self.instance.organization == organization:
+                raise HerdException(message="دامدار برای تعاونی مد نظر از قبل وجود دارد", status_code=403)  # noqa
+
+            elif self.instance.organization.parent_organization == organization.parent_organization:
+                raise HerdException(
+                    message="دامدار نمیتواند زیر مجموعه دو تعاونی با اتحادیه یکسان باشند",  # noqa
+                    status_code=403
+                )
+
         return attrs
 
     def to_representation(self, instance):