The Mansion or the Manor? Because you can't upgrade the Mansion (that's where Madison and Veronica live). Upgrading the Manor will be in a future update, and you talk with people the same way you did throughout Act One and Two. Find them, or go to their room.
Boss Girls have no special interactions right now, as they were supposed to just be one-shots. The refurbished battle system in the next update will give you the ability to interact with them properly.