Spacecadet - your DD reminds me of my sister and I have to say her behaviour left me so frightened so many times when she came for me - I know you love her but if she is behaving so appallingly to your other kids they deserve to be protected from her to - its just like domestic violence between husband and wife - it leaves scars forever!!
My BS (Big Sister) ended up in care - and she realised that it was shit - she had none of the power - no money, no love and no one reacted when she went ballistic - they were all used to it you see, she was just another in a long line of difunctional little cows who thought that they were in control.
They want to comer back so quickly then - they can have all the freedom they want but they soon realise that the only people who offer them anythig want something back.