There has been a bit of confusion around coaches pitching in our 11U division after a batter has been thrown 4 balls, please see excerpt from Baseball Canada rules, specifically the section in bold:
For 11U (Mosquito) low tier division only: 7.00 (a) No runner can leave his base before the ball crosses home plate or is hit. If there is a violation, the runner is returned to his base and the ball is dead. When the pitcher receives the ball and takes position on the rubber and the catcher is in his position, all runners must return to the base they were occupying. For 11U (Mosquito) low tier division only, the stealing of bases is not allowed. (b) The runner at 3rd base can reach home plate only if the ball is hit or because he is forced to advance. If there is a violation, the runner is returned to his base. (c) No bunts are allowed. If there is a violation, the ball is dead and a strike is called on the batter. On a bunt attempt on a third strike, the ball is dead and the batter is allowed to continue his at-bat. (d) For mosquito low tier division only, a base on balls is not allowed. After four (4) balls, an offensive team coach takes position on the mound, on the 11U (Mosquito) pitching rubber and pitch from above the shoulder for a maximum of three (3) additional pitches, independent of the count on the batter after which, the batter is called out. The strike count is carried on, the player is called out if he swings at a third strike. The player cannot be called out on a foul ball. · If the coach is hit by a batted ball, the ball is declared dead and the batter is awarded first base. The runners advance if forced. · If the batter is hit by a pitch thrown by the coach, the ball is dead, the pitch is declared erratic and is not counted. The player must continue his at-bat.