GOSH well she's your character, you should certainly do whatever tickles your fancy buuuuut

I had a thought that Billy would want to see what House of M was like, since he's heard about it- basically he'd want to know what it was like to grow up with Wanda and Tommy as a family together. So the twins would have Maximoff as a last name and call her Mom and act like TRUE BROS and yes. Shikki and I already talked and she's interested in that, so if you want to give it a try, it could be fun!