Hi Kimberlyk96
I am glad you are reaching out for support and advice here. It can be quite challenging indeed dealing with a BPD family-member.
You've been working hard on yourself as evidenced by you being in recovery from alcohol addiction for 8 years now

I understand your wish to speak to people who understand BPD and I think you've definitely come to the right place for that. Has your sister been officially diagnosed with BPD and/or perhaps some other disorder? Do you feel like your sister has ever in any way acknowledged that there might be something wrong with her behavior?
As far as communicating with your family-members, we describe some communication techniques on this site that I think can be helpful for you:
Communication Skills - ValidationS.E.T. - Support, Empathy and TruthHere are some excerpts:
Nowhere is the communication skill of validation more important than in interfacing with highly sensitive individuals, individuals with low self esteem or individuals who are easily intimidated. This is a very valuable tool for dealing with people with Borderline Personality Disorder.
To validate someone's feelings is first to accept someone's feelings - and then to understand them - and finally to nurture them. To validate is to acknowledge and accept a person. Invalidation, on the other hand, is to reject, ignore, or judge.
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We all know how to validate someone with whom we agree. However, where validation skills are most valuable is in dealing with situations where we disagree or are in conflict with someone.
In these situations, it can be difficult to find something to validate while remaining true and authentic to ourselves. It can be even more difficult to find the motivation to counter our own emotional instincts and our proclivity to reject, ignore, or judge. And all of this may be further complicated by the fact that we are tired, frustrated, fearful, or holding onto resentments.
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In a "BPD family" there are going to be validation issues. As the healthier family member, it falls to us to try to achieve some level of working validation in the relationship - to lead.
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Let's first look at the importance of being true and authentic to ourselves. If we can't be true and authentic, we are sacrificing ourselves for the benefit of another, and we are most likely enabling another person's dysfunction. This helps no one.
For these reason, validation is never about lying, it is not about being ruled by the emotions of others, and it is not letting people "walk all over us". We never want to validate the “invalid”.
Validating someone's thoughts, feelings, or beliefs does not necessarily mean we agree, overall, with what they are thinking, or feeling, or with their behavior.
So, the first thing to learn in validating others is to be able to identify something to validate in a "sea" of conflict that is both valid and important to the other person.