Years ago, there was a family who hosted Civil War Balls in a similar way that my family is currently hosting the Balls. Those Balls started out as family events just as our current Balls are family events. However, being that there were no rules in place about chaperones, in time, teenagers began coming without their parents. Later, entire church youth groups were brought in by the van loads and dropped off with no adult supervision. The people who were hosting the Balls could not do all the work to host and also supervise all the young people - some of who definitely need their activities monitored. That family finally gave up and said that they would never host again.
When I began hosting these events six years ago, some of the "old timers" from that first set of Balls warned me to always make sure that every teenager was chaperoned by an older, responsible adult. I have heeded these words and found that our Balls have remained pleasant and controlled, allowing me to focus on the dancing instead of worrying about whether or not the attendees were getting into trouble. I have found that everyone has happily complied with our chaperone rule for the mutual satisfaction of all.