How do you all share apartments and rooms with platforms on the Gallery?!

As the title says. Every time I try to share one, I can only share one room at a time, and not the "lot". If it's a room with a platform it splits the room as if it's more than one so I can't share the whole thing, what is the trick? What guru do I need to pray to for this ability?

Jokes aside I would like to know.