@Twingrlie - First, I have been a regular for quite some time; this is the very first time I have ever heard a mail box referred to that way. Did a local poll - no one else has either. Must be a regional city thing.
Second, you came here asking for advice, you have given same by various people and yet, want to argue. Your original question was regarding if a sub is entitled to a sub. I won't quote you since that would be against my personal religious beliefs, but I will say good gravy. You as a steward should have already known the answer. You then stated that said sub is coming back to a mess after her relief day.(paraphrased). You as a steward should know that a sub is entitled to a full day relief, just is as a regular.
I am also quite aware of the procedures which need to be followed to remove someone from the rolls; however...
nevermind.
Best of luck to you and all in your office.