Also, it shouldn’t be up to a coach to ‘challenge’ the roster of whoever his team is playing against. The kids should have to send proof of age to the governing body of the sport, get verified, and receive some sort of proof back that then either lives online or goes with them to every game the play - just like soccer and hockey. The concept of roster fudging and illegal guest players and even holdbacks in general is just not a thing for any other sport. Don’t put the onus on the coaches to challenge and enforce the rules.