@Carlos came up with the idea that we ought to have a backroom zero role 1-2 times a week. Their responsibilities would including finding people to fill the rota shifts, chasing up all repeats and confirming any ‘maybes’.
This could take place on a Sunday afternoon and a Thursday afternoon, would be my suggestion. This would mean a few hours each week could be dedicated to the task unambiguously. The task could also be done by more than one person if wanted.