Wow. This is hard. You have a hard choice. I wouldn't want my daughter to go back to an alcoholic mom. But, I wouldn't want this new marriage to break up either. This doesn't make sense. You're having to make a tough decision. So, first I would say to try to legally not allow her the right to live with her mom since she's an alcoholic. Second, I would sit down and have a heart to heart with your daughter about how that would not be a good choice. Third, I wouldn't put your kids above your spouse. In doing so, your marriage is doomed to start with. This needs to be discussed between you and your wife. You have to provide a united front. If the kids know they can separate you to and get their way, they will do everything they can to try. Kids naturally want their way and they don't see future consequences. We adults aren't much better, but we do have experience with consequences. Siblings will also fight and not get along. You need to try to teach them to get along, even when they have been "wronged". That's a hard task, but it is necessary. If in the end, your daughter stomps off like a spoiled brat to punish you and go live with her mom, then after dealing with her truthfully, you have to let her go and learn the hard way. If you leave your wife over this, you are only teaching her bad values and encouraging her selfish behavior. But, your wife has to agree to do the same, or it won't work. You will have another broken marriage and will become lonely eventually. Your daughter is going to leave you eventually, whether you like it or not. Your previous divorce has only allowed it to happen much sooner than you would like. But, that's the consequence of divorce, unfortunately. You have to teach your daughter right from wrong, good values, and how to handle life. That's your job. But, your job is not to stop your life in order to make her happy or to keep her from making a bad decision. You would be stopping your life and you wouldn't be helping her out at all. You'd actually be hurting her. Talk with your wife. Then, talk to your daughter firmly, lovingly, and truthfully. Consider bringing in your life coach to help the daughters get along. But, in the end, don't expect it. I never got along with my sister. I actually hated her until I became an adult and got over some things. My parents were awesome parents, but couldn't help us. It was our problem, our fight, our decisions. My parents stayed together and are very happy with each other. I can't imagine them separating just to make the house more peaceful. Your daughter is learning so many things by being in that house with your blended family. Invaluable things that will form her character, and can make her strong, if she's taught how to deal with it, that she has to deal with it, that sometimes we don't get our way, sometimes we are lied about, sometimes we suffer wrongfully. That's life. The sooner we learn how to deal with those things, while under a loving roof with lots of support, the better. If not, she can become a very angry and bitter person who suffers from manic depression and cannot handle anything stressful in her life. Don't shelter your daughter. Teach her. Making your marriage work and showing all your daughters what a good and loving relationship is like, that that relationship is the most important physical relationship on earth, is the best lesson you can give your kids. Your marriage should come first. But, I do understand your fear of her returning to her mother. Do everything in your power to hinder it, but don't compromise your life or your relationship with your wife. ** also, temporary cameras around the house might give a good wake-up call and open the air to communication and united front between you and your wife **