Why don't they get a room ?
Cool kid though Cool

Isn't the kid's bedroom a room?

Why it wouldn't be a room?

When it's a tree fort?

Does the kid fit in that fort or is he bigger than that?

What kind of "bigger" do you mean? ( ͡° ͜ʖ ͡°)

"Are you sayin' it's gonna get bigger when he gets bigger?"

what if she gets bigger too?

then probably ... LOL

what if he is big too ?

"Is it mandatory that I have to answer that question with a question?"