Hi there!
Your best bet is to put together games and challenges where adults and children need to work together in order to win. That could be anything from trivia questions to minute-to-win-it style contests. The idea is to get the moms involved by setting up teams and to keep it fun to keep the kids engaged. Depending on the space available, you could do a modified obstacle course or other physical challenges. I think the bottom line is an unstructured "dance'' for young children is going to turn into a free-for-all if the parents aren't participating.
We're having another mother/son dance for grades K-5 this year and we want it to be fun for both the boys and the moms. The past 3 years the boys have run rampant while the moms sat around and gossiped. This year we really want to do something that will keep the boys entertained and the moms involved. Does anyone have any ideas to share? We've done cowboy, pirate, carnival, and space themes. Any help would be greatly appreciated!!! Thanks!