you should help them behave in a reasonable fashion. i.e. if every one else is sitting, sometimes laughing, and clapping politely , your DS should not be whooping, jumping up and air punching at every opportunity? Also if audience participation is involved and we are asked to sing, your DC should not shout?
I went to a concert a few days ago and am still annoyed. It was a very mixed audience with just a few DC (my own DS included) most of whom just behaved like everyone else. But one DS (9 to 12?) behaved completely inappropriately through out, and his mum made absolutely no attempt to encourage him to modify his behaviour to the point where it was distracting for the rest of the audience and embarrassing for the performer (consumate professional though he was).
I felt sorry for the DS - he seemed completely oblivious to how every one else was behaving, in a very small hall - but surely his mother should have either helped him realise what behaviour is expected at this sort of do, or not brought him if he was for some reason unable to modify his behaviour? Bizarrely, the mother seemed to find his behaviour endearing - I think she was the only one. I went out to see a great performer and have a fun evening with my DH and DC, not to watch someone else's DC.
Incidentally the performer does plenty of shows aimed and children, and was pleased to see children in the audience at this concert.