Big hugs hun. I've not been in your situation but you sound really torn between the needs of your DP and the needs of your DD and I bet she is picking up on that. Dynamics have certainly changed in the family now you are all living together and she is trying to find her new place. I agree with a previous poster, I don't see child behaviour as manipulative, it's simply them trying the best or only way they know how to meet their needs. The more conflict there is around her behaviour (between you and your DP and the two of you and her) the more the cycle will continue.

I'm not sure how you get your DP to change tack or shift his perception from manipulative to unmet need though. There is a couple of great sites I have found with fantastic blog posts etc and I think you can contact the authors to ask questions etc (they have fb pages and so on). I'll pm you the links.