Hi K1313
My BPDmother knows that this person has spoken quite freely and nastily about her (as she has them) and despite yet another vow (she's made many over the years) never to interact with this relative outside of family gatherings, she's still seeking them out.
... .
I wondered if some of this might be my mother realizing that she doesn't have anyone else because of how many bridges she's burned (although I know she would argue she was the wronged party in all of those cases) and so she's settling for whatever relationship/friendship she can find?
It can be difficult to understand why a person with BPD does the things she/he does. Perhaps it is out of loneliness that your mother seeks this relative out. Another thing that comes to mind is that there might be something about this person that your mother admires (or is jealous of) and by association might feel like will also rub off on her. Are you aware of anything she might admire or value in this relative?