@AgitatedGoose Thanks. I think my DF must have talked her down from doing things sometimes (not all the time unfortunately) as the boundary crashing was always there but has gotten worse over the last few years as he's gotten progressively more ill.
I'll explain really clearly I don't want her to do x, y or z thing (always some sort of difficult behaviour most people just wouldn't do... non emergency very early/late night messages, unexpectedly phoning and putting Dad on, turning up at my house and posting stuff through the door because I didn't respond to a message quickly enough for her, turning up early and then trying to pressure me into dropping what I'm doing to meet her early rather than just sticking to an agreed time) and she'll always have an excuse about why she's had to do it, then will normally have some more goes at the thing I've asked her not to do, then doesn't understand why I've reduced contact.
I asked her if she'd like to chip in for a present for my sister when she had her first hospital appointment, this was before the cancer was confirmed. My Mum's first response was to roll her eyes and say she thought it was unlikely to be cancer, then she caught herself and agreed. But it was like she resented my sister for taking the attention off her and DF.
DF's progress between home, hospital, home with carers, hospital and then a care home was so, so much more stressful than it really needed to be because of all the extra weird behaviour on top. I'm not wanting to go through it all again with DM and I've spoken to her about having a plan for the future but I suspect everything will have to happen with the maximum level of fuss and drama.
I hope the electrician sorts things and you have a smoother holiday!