Substituting and replacing substitutes is even more of a mess than these posts say. Like others on this thread I've had a pair vanish as the game starts, perhaps because I was using +allavail+, then sub them with random volunteers on the subs list, then quickly replace them with local players. Something that has not been mentioned here is that the history for these local players can be wrong. During the game their histories can show board 1 as -ve instead of +ve. Their final histories can show board 2 numbered as board 1 through to board 18 numbered as 17, with 18 blank. Probably this happens because they were not the players of record at the start of board 1. Certainly seems that fixes on the whole substitution process are overdue.