Thank you for your reply!
In return, here is some reading to explain what comes to mind:
Indeed, it’s a trivial amount of money that’s at the root of the quarrel. A quarrel that was originally between “sisters.” We chip in for our parents’ gifts. Once, my sister “No. 1” asked if we could contribute a bit more. I replied that I couldn’t at the time of the request, that I needed to get my finances in order (between the sale of one property and the purchase of another). And that didn’t sit well with my sister “No. 2,” who quickly chimed in with some gratuitous meanness (as is her habit), her conclusion being that she would now prefer that I no longer contribute, since it’s always complicated with me… So as not to disrupt their plan, I contributed to the expense. In late September, my sister “No. 2” came back to my sister “No. 1” and to me for the purchase of our parents’ year-end gift (which she had bought without asking for our input). So I copy-pasted her remarks made several months earlier (namely that she no longer wanted me to contribute). And of course, I knew she wouldn’t like it, I knew it would trigger a “third world war,” but I was going through a difficult time in my life where I didn’t feel like “giving in.” Tired of always saying “amen” to everything, and especially to her and her gratuitous meanness… I admit I was harsh in my words, but I don’t regret having said them!
Where you feel she’s “wronged,” it’s that she misinterpreted my comments about a photo with all the grandchildren.
Anyway, she feels wronged about everything. She even took my father to task for how he cooked the pasta!!! And telling my mother that the only place she felt comfortable was at my maternal grandparents' house!!!
I fully understand that we need to temper our expectations, but everyone has made concessions: except her! She is the one who burned all the bridges. We all tried to have a discussion with them (since my brother-in-law did nothing to ease the situation, quite the opposite). They refused to talk to everyone and said each time: everything has been said!
What do you want us to do more?
It’s up to them (I’d even say: to them) to put in some effort, but there are so many of them that they risk drowning!!!
I'll keep you posted if the situation changes. 