They used to have lockins on prom night where I come from. The kids get a chance to be togather drug and alcohol free. They also got a chnce to win cool prizes. My daughter wona huge boom box and a tv.
If this is not available in your area. well ask yourself, do you trust your daughter? I would still talk to the parents and make sure they were going to be there and such. we cannot protect them from mistakes, we can only hope they have listened to our wisdom.
good luck. I know how hard it is to be parents of teenagers.