All of the books I read about BPD do not help me understand! Any thoughts?
Yup, a few thoughts.
First, you're looking at this logically like your daughter has one defined opinion on everyone in her life. But the truth is that since she relies so heavily on emotion, how she feels about others is probably always changing...sometimes by the minute.
For example, I have a BPD daughter and a BPD ex wife. The kid will call each of us and trash the other parent, sometimes within minutes of each other. She tells me her mom doesn't care about her and they only talk about shallow stuff, then I talk to my wife the next day and learn that they talked for an hour about relationships and health matters. This happens weekly, the same amusing cycles, and my ex and I now understand that one of us will always be the "bad parent".
It's okay though, we accept that and we work together to ensure we're both contributing to her life...regardless of who's turn it is to be hated. We did this yesterday when she lied to all of us about a "medical emergency" that was actually an elective surgery that the kid wanted.
Second, I have discovered in time that I actually enjoy being seen as the "bad parent" because all the drama and disordered thinking goes to my ex instead of me. When my daughter flips and paints me white, I get phone calls 5-10 times a day about everything that's wrong in my kid's life, how horrible her mom is since she doesn't care, etc. It's a ton of stress over absolutely nothing and while I love my daughter, I'm definitely happier when the drama goes to someone else.
So if your daughter is reaching out to your mom, that's great news. Maybe you're next in line, maybe not. But the important thing is that she's communicating with family and making amends. That allows you to be indirectly involved and that's much better than nothing, so don't see this as a bad thing. It's a new start regardless.
I hope that helps!