def _create_related(self, obj, related, subfield_dict):
        """
        create DB objects related to a base object
            obj:            a base object to create related
            related:        dict mapping field names to lists of related objects
            subfield_list:  where to get the next layer of subfields
        """
        for field, items in related.items():
            subobjects = []
            all_subrelated = []
            Subtype, reverse_id_field, subsubdict = subfield_dict[field]
            for order, item in enumerate(items):
                # pull off 'subrelated' (things that are related to this obj)
                subrelated = {}
                for subfield in subsubdict:
                    subrelated[subfield] = item.pop(subfield)

                if field in self.preserve_order:
                    item['order'] = order

                item[reverse_id_field] = obj.id

                try:
                    subobjects.append(Subtype(**item))
                    all_subrelated.append(subrelated)
                except Exception as e:
                    raise DataImportError('{} while importing {} as {}'.format(e, item, Subtype))

            # add all subobjects at once (really great for actions & votes)
            try:
                Subtype.objects.bulk_create(subobjects)
            except Exception as e:
                raise DataImportError('{} while importing {} as {}'.format(e, subobjects, Subtype))

            # after import the subobjects, import their subsubobjects
            for subobj, subrel in zip(subobjects, all_subrelated):
                self._create_related(subobj, subrel, subsubdict)