I may be devil's advocate here but he needs to put his child before anyone else. This doesn't mean I agree with the enabling part-but bottom line is it's his daughter and he should be able to help her in any way he sees fit. Not all 20 year olds are totally mature-I wasn't l, and that's partly because my mother abandoned me at age 15 for a man who didn't want me because I was "troubled". All that did was mess me up more. Frankly I would tell anyone I marry that my children come with me-drama or not, at whatever age-you've become the other parent. And if they aren't okay with that , they can forget about me.

Also, the way you talk about her-especially as a 14 year old child it sounds like you have an intense dislike for her . Which frankly may have contributed to her issues. I know it did mine.