AS thanks for the comments. W hasn't directly stated ^^^^^ but I feel relatively certain that is why she wants the adoption to take place 1st. She and S8 are close - as most young children are with their mothers - and I would guess that she wants to make sure that she has partial custody of him.
OK, that makes more sense. I guess I would suggest clarifying with her why she is doing this, I hope it's just for more access to S8 and not for some nefarious purpose like bilking you for more child support or something. WAS's are capable of some pretty heartless stuff.