Hi superld,
Dr. Blaise Aguirre is one of the leading experts on BPD in adolescence (who I believe is still at McLean's Hospital) and he writes in his book how BPD can be dx'd in adolescence. The traits my stepdaughter displays now at 25 were all present in her teens, and she was dx'd with bipolar (a dx that was recently removed). I wonder at times how her lives and ours would've been different if they dx'd her correctly when she was younger.
I recommend his book to start with, and also like When Your Daughter has BPD by Daniel Loebel because it focuses on the family system. Loving Someone with BPD by Shari Manning is also helpful and to get a close-up view of what your daughter might be experiencing, I recommend Buddha and the Borderline, which is a memoir by a woman suffering from BPD.
One of my favorite books for validation skills, which is an essential skill in any family suffering from a BPD loved one is
I Don't Have to Make Everything All Better by the Lundbergs because it teaches how to ask validating questions which has been a game changer for me as it validates emotions while placing accountability on the shoulders of a teen who resists taking responsibility.
Does your D15 have siblings? How are you and your wife holding up as you navigate these challenging behaviors?