Buddy, you know where I stand....SNAFU..... The twins turn 17 next month. Daughter started pushing the envelope long before my son. But he recently had a couple bumps (beers) that had me turn up the heat on him. They live mostly with my ex right here in town, but that doesn't mean I am an every day influence, unfortunately. Just keep her used to having rules that her parents set. ( I cannot enforce them when they have free reign at the other house....) You have your family under one roof, so you are ahead of many of us there. If she is on facebook, be sure to go through her page. It will give you a good idea of the friends and attitudes she has surrounding her. Some of these girls are absolutely viscous. And they're so smart that they'll post pictures of themselves partying...
Good luck. I'm waist deep myself!