Monday Hour One question

Hi! I’m working on my first week with Monday Hour One and something I’ve noticed is that one of my bosses changes meeting/call times quite a bit. For example, this morning she scheduled an “emergency” call at 3pm, then just now changed it to 1:30pm. Attendance on these calls is a job requirement, so I end up changing my schedule to match her needs. In her defense, she’s almost always doing that because someone else is asking her to change her schedule to match their needs! Generally I don’t mind changing my schedule, and I’m quite diligent about completing the work that was originally scheduled for that time, but to truly follow the MO1, my understanding is that I would not change my original schedule.
While ultimately I could refuse to be on any call not scheduled in advance, the result of that action could be the loss of my job (or simply not having information I need to do that job well!), which I’d prefer not to experience. What is your suggestion for a situation like this? Thank you!