Crew shifts

Hello!

I usually find solutions for my excel problems by my own, but this time this situation is cracking my head.

I'm working on a sheet that manages working crews, on a 24 hour basis but sometimes crews have to work for 12 hour periods in order for the same crew to work on different days in different weeks (eg: if crew A works saturday this week, then they will be off next saturday).

I'm trying to have a 2 week schedule that auto-updates with whichever crew is on duty that day (12 hour periods).

The other problem is every two weeks there are crew changes and sometimes the crew that is supposed to change is on duty so the auto-update should follow the "wrong crew situation" in order to restablish to flow. If the changing crew shifts on a day that they are not working, the auto-update function should follow the "normal situation" pattern.
If this wasn't enough, there isn't always a set day for crew changes, sometimes it's at tuesdays, sometimes wednesdays and less often other week days, so the auto-update should need the input of which day there will be a crew change and take that in account.

If you're curious, this is to be used to deal with search and rescue helicopter crew teams.

Thank you SO MUCH in advance for your help.

G.