I will say, that my sis no pics is kinda shitty when it comes to helping out with my dad. He gets around fine, lives by himself in central Iowa. But the last few years he's had a few surgeries that require someone to be with him for a couple days to make sure he's all good. Anyways, like 10 years ago he had a surgery and I helped him out for a few days.
So like 3 years ago, he has to have another surgery and she volunteers to take time off work and help him. When my dad told me that, I chuckled because I knew she was full of shit so I took the days off work anyways. Then boom, 3 days prior to the surgery, she's begging me that "something came up" and she can't do it (she was unaware I had already taken the days off in preparation for this). And now that's happened each of the last 3 surgeries for him. Turns out each time "something came up" it was her going out of town to do something fun, not anything that could have kept her from helping out.
Anyways, she's slowly working herself into getting less and less of an inheritance because of that nonsense/csb
That's the only thing I can think of that comes kinda close to what OP is describing.