
sabina,
I'm glad you found us--this site has made a huge difference for many of us here.
Can you tell us more about your sister and her circumstances so we can better help and guide you?
How old is she?
Has she been diagnosed with BPD? If so, is she getting therapy/treatment?
Are your parents aware of her BPD? What are they doing to help/support her?
How much contact do you have with your sister now?
This video is a good general start... . We can suggest other things when we know a little more:
Video-Tools to Reduce Conflict with a person suffering from BPD Wishing you peace,
GK