Ugh, I empathize OP.
I created a system w/ my mother because I had to tell her that I just couldn't respond to every need. (And I couched it in terms of what I had to be able to do for my kids, my job, etc... - which she understood.) So we talked in terms of red/yellow/green - green meant she was fine and didn't need help. Yellow meant she needed help but it didn't have to be me. Red was when I had to be the person who responded.
Talking it through (while sitting in the hospital after a full on code red but planning for lots of yellow and hopefully some green) by tasks/possible scenarios really helped get her on board. And it helped me also.
Good luck - this stuff is really hard.