Instead of having one family-friendly entertainer play for children and adults, you could consider having a childrens' performer in one venue and a college performer in another venue. The parents could enjoy their show, and the children in the next room could enjoy their own show. They have an incredible performance hall, a cozy little theater, a delightful coffeehouse in the student center, maybe a plaza or courtyard just made for an event. If your school has great facilities, and the students attend your shows there, then you can skip on to the next section. But not most schools.
Most schools have to make the best of whatever facilities they have.
If you've ever had 25 people show up for a show in a 500-seat hall, this may sound painfully familiar. Sometimes the best place to have an event is not where you would expect. That's why cafeteria shows are so popular on commuter campuses. That's why students will sit outside on the student center green to hear a band, but won't walk 25 yards to sit inside the auditorium and hear the same band in comfort. Maybe it's the novelty.