I, too, am glad you're willing to learn about BPD and be supportive of your daughter. I hope she gets Dialectical Behavioral Therapy, first designed for us. However, folks with borderline sometimes quickly fall out with their therapists, being sensitive to rejection, so don't be surprised if she jumps from therapist to therapist, making treatment difficult. I hope she won't.
I suggest you find some books about relationships with borderlines. One recommended to my husband was
Stop Walking on Eggshells.
I can assure you that other members here have children with BPD. Here's a group I have started to help parents of mentally ill adult children:
http://forums.psychcentral.com/group...ll-adults.html.