My MIL told me when I was pregnant for my 1st child that she would help in an emergency only. She was there in 20 minutes when OH was in bed with a slipped disc, and son was rushed to hospital for his appendicitis. She collected the other children from school, cooked tea and came every day until son was out of hospital.
When my DD and granddaughter lived with us it ended up with me being used to cover childcare all day every day while she worked, several nights a week while she saw the boyfriend and friends etc.
I insisted she found a Childminder and nursery place after resentment built up on both sides, due to very frequent arguments about me looking after DGD.
Things improved and we get on really well now. We do care for DGD when DD needs it and her nice circle of friends can't help.
People need to put down boundaries, and exactly what hours they are prepared to do, at the beginning, which is what I wish I had done with my DD
Patient Advice and Liaison Service

any day now