Well, here's where BM is gonna get the drama she was probably hoping for
So the inlaws haven't found out yet that their favorite grandchild (SD9) is now living at BMs fulltime. They just messaged DH asking if they can have her this weekend, since she would have been at our house next week normally. DH replied to them that she won't be here this weekend, but they can still stop by to visit if they want (they didn't mention seeing the other kids at all). No response so far, any bets on what it will be? I'm betting it'll be the same as when they blew off DS1 first birthday party because SD wasn't gonna be there and all of a sudden they'll be busy.
Also, I'm sure once they find out SD isn't living with us anymore BM will get her wish of having them go to her regarding SD instead of DH. Have fun with the looney, BM.
ETA: they ended up replying "they'll see what happens and get back to him." What a surprise.