                  'instance': obj,
                  'data': value,
                  'context': self.context,
                  'partial': self.partial,
                  'many': self.many
              }
              serializer = self.__class__(**kwargs)
  
              if serializer.is_valid():
                  into[self.source or field_name] = serializer.object
 
</s> remove         self.allow_delete = allow_delete
 </s> add         self.allow_add_remove = allow_add_remove
                'many': self.many,
                'allow_add_remove': self.allow_add_remove
                  'instance': obj,
                  'data': value,
                  'context': self.context,
                  'partial': self.partial,
                'many': self.many,
                'allow_add_remove': self.allow_add_remove
              }
              serializer = self.__class__(**kwargs)
  
              if serializer.is_valid():
                  into[self.source or field_name] = serializer.object
keep keep keep keep replace keep keep keep keep keep
 one-many writable nested modelserializer support 
rest_framework/serializers.py