>>712668076
>You can't hit their kid
You can publicly embarass them without striking them, Anon. You can also imply threats. Stand uncomfortably close and tower over them, closing the distance if they try back off. While keeping direct eye contact, tell them with a stern tone,
>Try something like that again, and see what happens...

Congrats, you just publicly embarrassed the kid, soft threatened the fear of God in them, and established that actions have consequences (at the very least according to your kid, and hopefully for others in the same stroke).