Hi Way Out,
I'd like to join
mamabolivia and welcome you to the BPD Family

I'm sorry you are struggling with your sibling we all get it here every person here has someone in their lives with BPD/BPD Traits.
Can you expand on your story a bit? Are you both living at home, are your parents in the picture, are you living together outside your family home, or do you live separately? Has your sibling been diagnosed with BPD? Have any of you (you, sibling, parents, family) tried Therapy? Have you done any reading about BPD? What kinds of behaviors are you finding most difficult to deal with at the moment?
Okay that's the end of the Panda's 20 questions I'm just trying to get more of a feel for what your situation is so we can better help you.
I'm glad you decided to jump in and post and I look forward to hearing more of your story.
Take Care,
Panda