So take the following example: player gets injured and requests to be substituted. Manager and substitute approach you at the half way line and whilst doing your checks on the substitute you ask to confirm his name and he isn't one of the names written on the team sheet so you refuse to allow him to come on.
After a while where the manager keeps asking to bring the guy on and you refusing to, they ask to bring the injured player back on. Do you allow this?
After a while where the manager keeps asking to bring the guy on and you refusing to, they ask to bring the injured player back on. Do you allow this?