Context: I'm starting a micro-school for 30-50 students. We want to manage absences and sick notes electronically. Parents should be able to schedule future absences and excuse past absences for their children. Ideally they should also be able to see which classes and workshops their children have attended and which ones are still outstanding.
How can I synchronize one central Google Calendar (that only the administrators have access to) with 30-50 other Google Calendars, so that parents see only the absences & schedules for their own children?