My girl would do histrionics from time to time, especially from about 12 to 17 (maybe earlier maybe later too, it's hard to recall). In retrospect, there seemed to be reasons for the outbreaks, it wasn't really just attention seeking it was indeed a coping mechanism, a way to cope with the pain. Also it was learnt behaviour. Past experience told her what would work to get what she wanted - unless there was a circuit breaker, it would continue on like that.
When my dh and I began with proper values based boundaries ... . when she was 31 (I know slow learner... . lots of reasons), that provided the circuit breaker for us. Then we learned about validation and over the time, we began to practise it. Now things are on the slow improve. And although sometimes I think it sounds as if I can do it, let me assure it has taken a lot of reading and thinking and help from people here and I still have so much to learn. But now we are able to work on our relationship with our dd.
Have you read the Lundberg's book: "I don't have to make it all better" it is easy to read. Here are some ideas from it:
"I don't have to make it all better" Also, there is an excellent book on boundaries: "Boundaries - when to say yes, how to say no to take control of your life" by H. Cloud and J. Townsend
It is hard to persuade your daughter when you are in the position you are in. Maybe you could entice here with the interest of Neurofeedback Therapy - explore about it first, so you know what it's all about. You have a couple of years of opportunity until you lose legal responsibility, it would be good if you could make progress in this time.
What do you think?
Vivek