First stop calling your kids heavy it can't be good for their self image. Nah I'm just joking I don't have kids and can't possibly tell others how to parent. But I do think getting your kids involved in a sport like this is a good move.
The reason I don't support a Junior Class is twofold.
EU Privacy Law: I am not a lawyer and nothing I have ever said or will say is legal advice.
Are juniors actually a class?: