This was new to me

[umpire99]

FED rules. The DH (who is batting for the pitcher) reaches base. The offensive coach enters the pitcher to run for the DH. After one pitch, the coach requests a courtesy runner for his pitcher. Can he do this? Some of you might say, "Why not just put in the runner for the DH and be done with it?" If he did that, he would no longer have the runner as a legal substitute later in the game.

What does everybody think?