I'm wondering if things got worse when fiance and the k ids moved in. Those are hard changes for a troubled kid. Heck, that is difficult for a "typical" kid. Now she has not only other unrelated kids in the house, but your new child. Think about it...a new fiance (supposed mother figure) and THREE step sisters? Plus YOUR new baby? That in my opinion is just so much to throw at this child. How long ago did this fiance become a part of her life? When did she move in?
Your daughter's mother has already abandoned her...to drugs. Does she like your fiance or resent her? Does stepmother act as an authority figure? If I were you, I'd tell fiance that you will parent her yourself and that she can be a friend, but not a disciplinarian. No point in making her the evil stepmother. My hub had to be a friend to my kids when we first got married. They did not want to listen to him...they did not consider him their father...they had a father. It worked out a lot better that way. Ex and I parented them and he just was there for them in a friendly way. How does your daughter like having three step sisters? How old are they? How does she feel about the baby?
It is kind of asking too much in my opinion for friends to take in your disturbed child. in my opinion it was a bad idea and I'm not surprised it didn't work. These kids are too difficult. Residential Treatment Center (RTC) may be the only way to go. Now that there are other children to think about, it isn't good for them to see her acting like she is. Yes, you have to chose between fiance and her kids, unless fiance is very committed, or your children. You can not lose your baby. Fiance has to allow you visitation rights. You can only lose your fiance and her children and that is something you may have to do...or maybe she is loving enough to understand and hang in there. I agree that counseling for all is a must.
Also, I think it would be a good idea to go to Al-Anon or Narc-Anon to get some great advice from those also in the trenches. You can pick up a lot at those meetings and also get help for yourself.
I hope things get better. Please keep us posted. We do care.
I was going to say pretty much what MidwestMom says, only she said it better. I have explosive/anxious teen daughter and blended family. We blended when she was a lot younger but there are still issues, so I can sort of relate. What struck me with your situation is that there is a new live-in girlfriend. New baby. And THREE other daughters who now live with you. So you have 4 other girls and a baby living with you and your daughter.
In her eyes, it used to be you two as a family unit, and now she is forced out of the family (literally asked to leave her home) that is now filled with other daughters whom you are now parenting. She did not ask for that and probably had no say in the matter.
You can't give up on her. Her mother already did.
She has to be a priority in your life, and she has to feel like one.
Hang in there. Don't give up on her no matter what she says or does. Not at this stage, anyway. She is angry and has an immature teenage brain, so she is going to do and say things that sound like she is making decisions, when really, she is just hurt and angry. ("Do you want to go live with Elsie and Ned and enroll in a new school?" "Fine, whatever.")
It is hard to have compassion when they act so nasty, but you have to dig down and find it somewhere in you, even when her behavior rocks the whole house. When I say compassion, I don't mean letting her bad behavior slide, but the compassion that makes you keep fighting for her. Remember she is still your little girl. : ) Keep us posted.