Wow. Good luck to you! I am a floor nurse so I don't have that much work, thank goodness.
However, I think you may have answered your own question. Apologize but tell your patients that to keep everyone safe you and happy you have to stick to stick to the schedule. It will also make it easier for your co-workers if everyone keeps the patients on the same schedule.
Also, I've gotten REALLY, REALLY sick of being the ones that always suffer. It is unreasonable that managers and owners consistently expect nurses to live and work like animals. It's not right. I've gotten to the point that I try to file an incident report every shift short staffed to have IN WRITING that I made the managers aware, repeatedly, that we are short staffed. And I've begun to email my manager whenever I have a short staffed day and tell her how short staffed we were and that I didn't get lunch. I have twice been counselled about two policies I screwed up on in the last few weeks. My opinion, I was super short staffed. Had I not been working my tail off with an unsafe assignment, patients could die. So you know what? Staff the floor well. If you choose to staff terribly, I don't want to hear your hand-wringing about policy and protocols and MINOR policy issues. YOU SHOULD BE THANKING ME NOBODY DIED!
To me, the worst part is that, on my floor, we're not allowed to tell the patients that we're short staffed. So I have to be like, "Sorry I kept you waiting forever. I was eating bon bons and watching TV."
I'll probably get fired eventually. But I refuse to be treated like a beast of burden. Meanwhile the managers are getting paid vacation and 8% bonuses while the nurses and patients suffer.
Forgive the rant!