There is strength in numbers. Engage kids in planning their special evenings, working within clear and safe guidelines set by the adults. Teenagers need to feel a sense of control of their plans, but they also need to know their parents care enough to put some limits on those plans. When possible, avoid kids' driving. Even without the presence of alcohol, the excitement of these special evenings can make driving risky.
Some parents chip in to rent a van or a limo for groups of kids.
Or they help to arrange a lock-up party at a safe place with lots of fun activities. However you define your guidelines for these activities, be clear and firm in communicating and enforcing the rules. Above all, let your teenager know it is your job as a loving parent to look out for their well-being, whether or not you're popular in the short run. Then be patient in the belief that someday your children will thank you. And know that, on some level, they may even be relieved right now that you have saved them from a difficult and possibly dangerous situation.