Hi graceandpeace!
Welcome to our online family! I'm so glad that you've come to share your story and to join us in this journey. It really is challenging. How wonderful that you are seeking understanding so that you can help the relationship between you and your sister.
I've found in my own life that as I began this personal journey to understanding, somehow it has managed to leak out to other family members, thus aiding us all in understanding and healing from my uBPDm. I liken it to tossing a pebble into water, and seeing the rings moving outward from the continued affect of that tiny stone.
I'm including a couple of links that I think may be helpful places for you to start.
https://bpdfamily.com/content/communication-skills-validationhttps://bpdfamily.com/content/ending-conflict Have you read any books about BPD yet? Is there a T in your area who is familiar with Borderlines? I have found such great help and validation with my T as I work to overcome the effects of a pwBPD. Thank you for wanting to make a difference in your own life and protecting yourself in a healthy manner.
Wools