It's a load of things, but a couple of examples
I was hosting Easter (for 11) mostly my sisters family (she said she couldn't do it as people would have to travel. I asked if she could bring one dessert, I had to cajole her to do it, she couldn't travel with a desert, why not you're in a car and a cheesecake etc is easily able to be transported. I'm made to feel unreasonable for actually insisting she could.
I have a sister who is visiting for a long while, she's been pushed onto me. I had to go to the office one day, asked my brother to come over to take her to lunch (she's not well and needs to be encouraged out of the house, which I do a lot off). She's also very lazy in the house doesn't clear up after herself etc. he came over, didn't take her out, she made him lunch, left everything out on the worktop, plates, cups, glasses etc, used the last sandwich filler that my DH was going to use for his sandwich the next day (shopping was due the following day). DH got home before me and had the right hump, we ended up having words. So my asking him
to take her out to lunch ended up causing us more work than if he'd not bothered.
I entertained both days the previous weekend, because people wanted to be with my sister, but I ask for one meal to be provided elsewhere and it doesn't happen.
But I should ask for more help? I don't get any at the moment, even when I do ask. It's either not done or I have to keep arguing that it is possible.
I admit to feeling very upset and put upon, I know I've got to completely step back and if they can't/won't organise anything, then we won't be meeting.