@Impromptu Slog Children of BPD support group (of which I am a member - my comment @22 was based on experience):
If you have not, read "Stop Walking on Eggshells" or the "BPD Survival Guide" by Randi Kreger OR
"Loving Someone with BPD" (Manning)
Kreger gets the terrible feeling of living with this issue better. Manning makes the picture seem rosier than it is, but her skills (based in DBT) are good and helpful.
Also there are some Family of BPD support groups online - https://www.bpdcentral.com/support-group…
In my experience, self care, setting limits, and effective communication go a long way in improving relations, but they won't give you the parent you wish you had.