Should you call them out on what they have said or just let it go. The thing about my dil is that she claims to have "issues" with my husband and I which prevent her from coming to visit us. She told my son and my daughter the issues which are from years ago. They are the following: When we had a party to celebrate their marriage at our house we were not welcoming to her family, a guest accidentally mistook her mother for a server. That was 6 years ago. Also, when they were dating I happened to mention to my son that I ran into his old girlfriend that he had broken up with 4 years prior. But on the flip side we are welcome to come and visit them anytime. Is this type of contradiction part of BPD?
One thing I've noticed is that while pwBPD can be incredibly insincere (split, turn on a dime, rewrite history, make you question your sanity and reality), they can sniff out a lie or insincerity in a heartbeat in someone else and make heads roll. So gifted that way
But I have another idea for you. "Calling out" a pwBPD never works, at least IMO. Whatever issue there is will never be her fault, she will never claim any responsibility for her part, can never see that she is perpetuating drama by bringing up the (trivial) past over and over and over again. And really, she
actually feels incredibly hurt by something minor that happened years ago. At least that's the nice way to see it. She's an empty pit who feels abandoned all the time if she has BPD. That sucks. I would not want to feel that way constantly. Plus, it's leverage over you. May explain why you are always welcome at their home--she's in control there or feels more comfortable on home turf, she gets to be the more "welcoming person." It doesn't have to make sense, really though!
Similarly, my uBPD mother operates from chaos because that's how she grew up and chaos=love. If we're peaceful and calm, something must be wrong, so she creates drama to feel SOMETHING. While it seems crazy to you and me, pwBPD are emotionally about 2 years old. Grudges and tantrums are very real to her. BUT, they crave attention and sympathy. They love playing the victim. If you really want to bury the hatchet with DIL and help her move on, perhaps acknowledging how incredibly hurt she feels is a step. Pull her aside, tell her how much you care about her and want her/her family to feel a part of your family. You've heard what she's said about that party and her family and after some thinking about it, you now get how hurtful that was. Apologize *sincerely* for any part you or your family may have played in making her family feel less than welcome and for the ditzy relative who mistook her mother for a server. Even if it was totally all her perception and not based in any reality. Ask if there's anything else she is upset about, and really listen. Acknowledge it (even if you don't agree with it! Acknowledge her hurt). "I can imagine how much that must have hurt. I didn't know you felt that way. You were really sad. I get that now." Whatever. Then find common ground if you can. Use SET. It sounds like you would like to have a better relationship with her because she is a part of your family and you respect that she is married to your son. You had a party to celebrate their marriage, for goodness sake!