I must have been a big threat to my late DH's only sister. She was all too frequently unhappy with something I did. We lived with the in-laws for a year back in 1994. SIL and her husband lived in a mother-in-law unit out back, and DH and I and the girls lived in the main house, and boy oh boy, it was TIGHT. SIL and her family had been living there for several years at that time. When we moved in, because we were moving into the main house (already fully occupied and fully 'furnitured') ALL of our things went in storage but the clothing in season. Out of season clothing, all holiday and dress up stuff, furniture and most of the kids toys - all of it in storage.
And Christmas rolled around, and I couldn't find the stockings in storage. DH had his own stocking from when he was a child, I had mine, and I had gotten or made fun stockings for my children as they were born, and I could not find them in any of the bins and boxes. Most frustrating. So, I trundled down to the local fabric store, got some felt, some faux white fur, some snowflake sequins and made stockings for my daughters so they would have stockings for Santa to load up with little things for them. DH and I, being grownups, would deal with not having our personal stockings.
SIL went to my MIL and complained that I had made stockings for MY children and not for her children, and it was grossly unfair and really rude of me to do this. MIL came to me and asked me why I hadn't made stockings for my niece and nephew? I explained that it had never occurred to me that SIL would not already have bought stockings for her children, as they were no longer infants, and that I had only made the felt stockings for my children because I couldn't find the 'good' stockings they already owned. Why would I assume SIL, who hated home made, hand made things with a fiery passion of undying hate, would want ME, the hand made queen, to make her children one of my substandard stockings? Cue the cat butt face...
MIL said her daughter was unhappy and MIL wanted me to make my niece and nephew stockings, please and thank you. I explained that I couldn't afford it, but if she wanted to fund this project, I would go and get the supplies and make them, but it would take me until nearly Christmas because I had other things I needed to get done in a timely manner.... Niece and nephew used the stockings that year, nearly identical to the stockings made for my own children, and I never saw them again.
Hindsight tells me MIL was between a rock and a hard place. Her daughter had expressed hurt (or anger, she never said anything directly to me, so I don't know what she said) and demanded that I double my effort and make something for her children. I was offended at being accused of being selfish and unthoughtful, and I really and truly didn't understand why SIL didn't just walk up and say she liked what I'd made my kids, (or her kids liked them) and would I pretty please make 2 more for her children. But being direct was never SIL's way; she always ran to mommy and pitched a fit, and made trouble about something that could have and should have been handled very easily with a simple request (and offer of a subsidy or paying for supplies). As a result, while the cousins are all friends (not best buds, but friends), SIL and I no longer talk at all, other than platitudes to keep the peace at the last family wedding.