Wow, being a parent of a 12 yr old girl and a 17 yr old boy I feel for what you're going through. My boy is my focus right now. The girl seems ok for now. I'm trying to steer her away from the friends that seem a little to "sly" and get in trouble.
I would be sick if my daughter was doing what yours is.......I don't think I could handle it. I wish you all the best. I would say be firm but don't push her away even further.
Custom88 said it best.
2003 Granite Metallic SSEI 14.5@96
3.5 pulley, Intense PCM, 180 stat, Autolite 104'*, Intense FWI, Borlas, custom Y and chrome Tips, Aeroforce Scan Gauge, MBQuart HU, 12" Power Acoustic Sub, XM Roady XT, Silverstars
(former GTP owner)