@craig77
What kind of store are you in, Extra, super,Metro or Express?
It kind of looks like your previous or current SM has either not followed a process a few years back,( when a lot of stores lost there night team) or has made up shifts to make things easier for them at that time,
Which is now coming back to bite them.
From what you have put, it’s sounds like your in an Express, as one near me has a set up similar to you, even though they shouldn’t.
If they cannot replace the other colleague, what happens when one of you are on holiday/sick?