NFHS Question
 

NFHS Fast Pitch Softball. Baserunner on third and 1 out. Batter hits an infield grounder to F5. Runner on 3rd starts to run when pitch leaves pitcher's hand. F5 fields the ball and throws to first to try to retire batter/runner for 2nd out. The field umpire, home plate umpire and catcher all turn to watch the flight of the ball thrown by F5 toward 1st base. The home plate umpire has moved a couple of steps toward 1st base and the catcher is still in her position behind home plate. Everyone is watching the play at 1st base. The baserunner on 3rd steps on home plate and then runs over the catcher. As we say (she de cleated the catcher). There was never any play at the plate. Should the baserunner on 3rd be ejected for the unnecessary contact.

If as you say "Everyone is watching the play at 1st base.", then neither umpire saw the incident. So, no ejection.