Sims 4: Switched control while on University

@bossnanni  Yes, you can switch back and forth between households while the child is at University.  However, the child will probably not get good grades, maybe not even passing grades, while you're not controlling him.  You might come back to find there's not enough time left in the term to get the grades up, or that the sim is already on academic probation.  Point is, if you want the son to do well at University, you'll need to control him while he's there.

If you don't want to miss so much of the main sim's life, you could disable aging while the child is at University, then reenable it after he graduates.