Deal with kids everyday that are on different ASA and HS teams. Not a big deal. They tell me what their coaches have them doing ... sometimes I agree and I reemphasize what I want extracted from the drill ... sometimes I have a slight modification ... sometimes I disagree with the instruction given with a drill, but find a way to make the drill work for the hitter ... sometimes I tell the kid that the particular instruction is destructive and that we want to get through a particular drill without actively learning anything from it.
Remind the kid ... they are responsible for their swing. They will receive swing advice from many well meaning people throughout their playing time. At all times, they are the one's that are responsible for their swing. Filter out the bad, and filter in the good ... keep swinging and keep learning.