Actually, people are running off on tangents that are immaterial again.
This is Virginia. The child support order, except in extremely rare cases, is SET by statute. The law doesn't say you owe it until GRADUATION. It says until the child is 19 or "while the child is a full-time high school student."
Again, this boils down to what the district intends to do with the seniors. If they are going to claim that the diploma requirements have been met by what has transpired up until the schools closed (which I suspect is likely in most districts), then the support obligation would appear to end at the day classes stopped. If there is some "full time distance learning" involved, then one might argue the obligation continues until that completes.
Again, absent knowing what the individual district intends to do, we can't give an answer.

