Partner CANNOT plan ahead

My partner and his BM seem absolutely incapable of planning custody beyond month to month. And they write the schedule at the end of each month. AND they do it bespoke every month; always different. She has other kids with another BD, and they don’t plan in advance at all. And she wants all her kids from all BDs together on the same custody schedule. Is this normal?? My partner and I are long distance at the moment, so basically my schedule can never be planned in advance, and I am at the mercy of my partner’s schedule, his kid’s schedule, his BM’s schedule, BM’s other kids’ schedule, and the other BD schedule. I am going to lose my 💩!