She is smart enough to know "new house, new rules." It shouldn't be a problem IF everyone is consistent about it.

My first dog Sheba (the best, smartest dog in the whole wide world) learned that when Grandma moved in with us, Grandma just could NOT abide a dog on the couch. This was Sheba's own house, mind you, we didn't move, just Grandma moved in with us. But Grandma scolded her ONCE, and that was all it took. Sheba was never on the couch again when Grandma came in the room.

Sure, there might have been a warm, dog-shaped spot with black fur in it on the couch, but Sheba was curled up on the floor!

In Grandma's defense, she really grew up believing that dogs didn't even belong in the house. And the bulldogs my dad and Grandpa had were all too short-legged to climb up on the couch, anyway. And being bulldogs, they weren't all that ambitious, so followed Grandma's rules about dogs and furniture without challenge!

Mia will learn, I am sure. It's just another part of the big adjustment she'll be making.