My son comes with me, he's 4'4" and just old enough to take part. He's always in the front line of any fight. If I loose him, I just listen for the worst of the fighting & he's usually there.
The other older guys always help him & do offer advice which I always takes on board.
when people ask me "Should we go easy on him?" I always reply "No, if you get a chance to, hammer him" he wouldnt hesitate to shoot so treat him the same.
Last time we were down, he got shot in the head for three feet away & he was well chuffed that he has a scar to show his mates at school.
As long as kids have the right direction & play well I could not care less how old they are, kids are tougher than we give them credit for.