T on parents?

[just another ref]

NFHS rules: A T can be called on team supporters but "care should be used not to unduly penalize the players for the actions of idiots." (paraphrased)
If screaming is all it is, my advice is get used to it. It's the rule, not the exception. If the behavior is over the top, let game management handle it. If you do resort to T'ing the crowd, I would think it would only tend to make matters worse. And the T is a team T, not to the coach.

If necessary, point out the offenders, let game management take care of it.