Hi Phobos, welcome to the bpdfamily
Im sorry that these issues have led you here but you are in the right place for support and guidance, and its great that you care about both your daughter and family so much.
So much of what you describe is so very familiar to parents/members here, and we often arrive here at a pint of crisis or needing validation and direction.
There are a few really good books that will help you to understand BPD, you may locate some of your experience in this reading, and without a diagnosis, I would encourage you to articulate your concerns with a therapist.
Shari Manning "Loving Someone with Borderline Personality Disorder", and Randi Kreger, "Stop Walking on Eggshells" by Randi Kreger.
Personally, I have found a holistic approach which includes self directed learning, a therapist and support crom close friends to work for me.
Importantly, I have so valued the input from parents here as they completely "get it" and Ive benefited so much from their journies and wisdom.
Please lool after yourself, BPD (traits of BPD) pesent as significant challenges, that requires self care and resilience.
We look forward to hearing more from you. Take care
Merlot