Hi Mama D,
I understand what it is like to have an adult child with BPD, and struggle with opposing parenting styles.
My choice was to learn all that I could by reading books and joining this site so that I can know that I am doing the best that I can with the most tools that I can find. My husband doesn't understand it but I don't fight with him about it. It's too overwhelming for him, I don't think that I could ever get him to learn all this stuff so I give him really small doses. Dealing with BPD can be exhausting! We are now at the stage where he (my husband) at least understands that I know what I am talking about and he backs off with his opinions. Mostly
I believe that there is hope for your daughter. I believe that with the right emotional support she can go on to live the independent life that you hope for her. We are here to listen.