She "builds" them a house bigger than her (she's laying beside it in the picture so you can see how big the treehouse is ;-) ) and develops an entire story of how their lives will play out, what rooms they will need, where the Dad's study should be so that it's far enough from the play room to be quiet, etc.
I had no idea stickers could become "pets," but then again, I don't live in Gracie's head. Wish I did. It's quite delightful in there. :-D