this whole thing with my son and stbx's gf has me unsettled and I want to do something!! my son is utterly miserable.
This is the sitch in a nutshell

March• legal sep. signed, visitation set up while he was with then single no kids ow

Aug/Sep• messy breakup with ow, he buys a townhome

Nov 2• Comes to pick kids up with new gf kids have never seen, same night she sleeps over, later on I realize she will be living there for good. My son is horrified, upset and uncomfortable with gf, acting up (he has always been a very good boy)

Nov.11 • s10 tells me gf's kids will be moving in in Jan or so, stbx says maybe in Jan or a couple of months. My kids share a room now, but when they come they'll move my d5 to a room with her d9 and my son will share room with her s6.

The woman bosses my son around all the time, overrides whatever desicion stbx and I make about kids. My son either stays in his --for now-- room and sulks when he is there. Stbx says he has to get used to it and that it's his life to live (stbx's) STbx taking his time calling the C he agreed he'd talk to with s10.

My sitter (remarried, has 2 kids, married a guy with 3) told me that in the best of circumstances their kids needed a year to get used to the new family, that I should go to court and make it know that stbx is showing poor parenting decisions that are affecting the children in a negative way, to not let kids go to their dad (I think in her case her new H's ex was a psicho w/knife and that's how they let him keep kids)

If I go to court this will get really ugly, and I doubt they will give me full custody and it might just hurt kids and any chances I have of flexibility with stbx when kids/I would like to see each other. He is a total jerk and will make things horribly difficult. If I loose I won't have a leg to stand on.
Sitter tells me that I still have a chance to do something before D is final.

I did decide to talk to stbx in good terms suggesting I keep kids an extra sunday and wed. night, he already changed his mind about letting me have kids an extra sunday (thanks to gf) so I dont' know how well that's going to go.

I can't resign myself to just watch as my kid is thrown into heck once those kids come over, I know stbx will not stand up for them to gf when problems arise about kids. I HAVE to do something.