Lilly can hear, she can see too. She just can't speak.
She uses sign language, and Uma, and Matt can only understand it.
She likes to sleep, and will curl up in someone's lap, since she's pretty small.

Scenario-
Matt had said something about a mute girl coming to live with everyone. You were kinda fine with it, but of course, Tom said he wouldn't be able to talk to her if she can't speak for herself. Oof. But, when the girl arrived, she made a movement with her hands.

What do you do?