diff --git a/xos/tools/apigen/api.template.py b/xos/tools/apigen/api.template.py
index d0852db..9f5123c 100644
--- a/xos/tools/apigen/api.template.py
+++ b/xos/tools/apigen/api.template.py
@@ -148,7 +148,7 @@
     id = IdField()
     {% for ref in object.refs %}
     {% if ref.multi %}
-    {{ ref.plural }} = serializers.PrimaryKeyRelatedField(many=True,  queryset = {{ ref.camel }}.objects.all())
+    {{ ref.plural }} = serializers.PrimaryKeyRelatedField(many=True,  required=False, queryset = {{ ref.camel }}.objects.all())
     {% else %}
     {{ ref }} = serializers.PrimaryKeyRelatedField( queryset = {{ ref.camel }}.objects.all())
     {% endif %}
diff --git a/xos/tools/apigen/hpc-api.template.py b/xos/tools/apigen/hpc-api.template.py
index 2bb8b8a..ed252b8 100644
--- a/xos/tools/apigen/hpc-api.template.py
+++ b/xos/tools/apigen/hpc-api.template.py
@@ -146,7 +146,7 @@
     id = IdField()
     {% for ref in object.refs %}
     {% if ref.multi %}
-    {{ ref.plural }} = serializers.PrimaryKeyRelatedField(many=True,  queryset = {{ ref.camel }}.objects.all())
+    {{ ref.plural }} = serializers.PrimaryKeyRelatedField(many=True, required=False, queryset = {{ ref.camel }}.objects.all())
     {% else %}
     {{ ref }} = serializers.PrimaryKeyRelatedField( queryset = {{ ref.camel }}.objects.all())
     {% endif %}