What about doing the management's job for them: if you could find someone happy to do the late shifts and the shifts you don't want, perhaps students, and swap with the ones you want and present it to them as a done deal.
Thanks for the idea but I doubt whether they’d go for that as our students come and go too much, they’d need to give it to a full timer or a permanent part timer and change our contracts. Most of my colleagues prefer the earlies!
