But the coach can't completely lay off the kid either. The private instructor could be on the wrong road. The team has to have some group sense of how to attack skills or else the team will have a jumbled approach to playing the game. They also get a mixed message about whether to listen to the coach at all and that certainly won't work. You have to know and say enough to get the kids through games with solid performance. Or else team practice is a waste of time and should just be canceled.
I understand the perspective and the coaches should be treated with respect. But in this case the coach is not respecting the child or the wishes of the parents. If the parent tells the AC that his instructor is messing up his daughter, the AC should stop immediately. If he doesn't the parent should take it up the chain of command or take his daughter off the team until the conflicting coaching stops.
It sounds to me the AC wants to be right more than he wants to help the child be a better player.