pregame dunk

[gj56]

Situation in boys high school varsity game A5 dunks during warmups we inform coach A that we are going to to start game with a T and he loses his coaching box privleges for the game. He is not happy but he knows the rule and he understands. We then inform coach B of the situation and he asks if anyone can shoot the T . We say yes. Starters are introduced and we're ready to go coach B then sends a player off the bench to shoot the T. Coach A goes ballistic yelling there should be a T on team B for an illegal subsitution . Coach B says that we told him anybody could shoot the free throws. After a lengthly conference we told the coaches that we misinformed coach B and a starter would have to shoot the free throws. We sent the sub back to the bench and started and finished the game with two very angry coaches. My question is in this situation does a starter have to shoot or can a player come off the bench to shoot .