What to do when a coach teaches something blatantly wrong and dangerous

[radness]

OK I'll say it. I am not sure it is ever OK to allow parents in the practice area. Observe and discuss away from everyone.

Add
this is more of a story about if a Coach is going to respect that you have a separate instructor. it's hard to draw a line for some coaches who believe things should be done their way versus any successful way. firstly remember people are trying to help. But I think too much help can get confusing and the OP pointing that out . think was on point. *however should not be discussed in front of the ~kid ~who does not know how to interpret what's going on yet.
a little respect goes a long way! Or should by all people.
coaches feedback should be regarding either positive or negative results of what the batter is doing. Then that feedback from the coach can be taken to the instructor. I say this again and again
* look for results!
Especially young people most of the time take longer to figure things out because they are key word developing.

when you go to look for your new team LOL

need to have specific conversations with whoever and all coaches there are going to be to make sure everybody is on board with *okay to have your own instructor.
Coaches will tend to think it's my team my players my way.

Thank goodness not all coaches / people are like that.