Substitutions during Free Throws

[vawils]

Problem in last nights game between the clock keeper and a nasty coach of one team. What is the ruling on substitution for the free throw shooter during free throws. Several times the ball had already been put at the free throwers disposal and the coach would run a player to the scorer's table and then if the shot was made the clock keeper would buzz him in. Also some players were sent late for non-shooters. Doesn't the player have to be at the scorer's table before the ball is at the shooters disposal even if he is substituting for the shooter??. I didn't allow the substitution at one point saying he reported too late and the coach went crazy . Also sent a player back who just came on the court during time out without reporting. The clock keeper wasn't much help all game because he was just letting people in. I talked to the clock keeper and the coach about no player entering the court until beckoned. Things got a little better but the coach only marginal complied with my direction and was a fun one all night. I would appreciate clarification on this rule on substitution during free throws, so I can handle this better next time. Thanks.