I've turned the university housing to residential so the students can live there in between terms. So I'll play them through a term and then I don't re-enroll them until I play that household again. I also have multiple students in a household but I don't have to enroll them all at the same time. Some of them may just work part-time jobs while the others are enrolled in classes. I play with aging off and age sims when I want to so I don't have to worry about anyone aging up before I'm ready for them to.
