Multiple entities... Or ONE FAPE FORM TO RULE THEM ALL

FAPE is the greatest thing since sliced bread to me. If one wants to edit one field on an entity, one no longer has to throw the whole entity's edit form out. And if #2451015: Support multiple fields for custom applications gets accepted, it can handle multiple fields of an entity.

I was wondering if the maintainers would support a patch providing the inverse functionality too... Combining fields from multiple entities. It would be a super simple patch to FAPE and an annoying thing to do separately.

It would solve lots of use cases in which entity references are used, field collections, etc. Something like...

fape_field_edit_page($entity_type1, $entity_id1, $field_names1, NULL, $entity_type2, $entity_id2, $field_names2, NULL);

...And all the right validations (and only those) can be called, etc.