Wow. First, let me start out by explaining the adolescent brain. The child brain doesn't fully develop until about the age of 25. The gray matter in the frontal part of the brain is not there yet so he/she cannot reason or be reasoned with. Your husband seems to aggrevate the situation by being an "enabler" to her. Your other children are watching (they are like little sponges, and absorb everything!)
She needs inpatient treatment. There is NOTHING you can do for her except give her tough love. She is already well into her addiction and is quite capable of drawing the entire family into it as well. Here's some suggestions to start:
1. Her mom is not allowed near or around your home at anytime. Seems to me that she is exacerbating the situation.
2. Your husband need to grow some balls (sorry about that), but he cannot make choices between his child and his family!. This is what the daughter wants, and it seems she's winning.
3. Take your keys and lock up your home when you leave. She should remain out of the house while you all are at work. She will begin to steal items and money (if she hasn't already). You and her husband cannot afford to pay for her to "play house)@ your convenience.
4. Insist that she goes into treatment or else.... SHE MUST HAVE A CONSEQUENCE!
good luck