My SO's uBPDxw is incapable of co-parenting she can not cooperate. The court seems to have recognized this and awarded each parent decision making for specific things. My SO is responsible for Medical, Dental and Education his ex is responsible for Vision, Gynocological and Therapy. They each handle the items they are responsible for... .a parallel parenting model.
If you want more information on parallel parenting there are several threads on the subject, just plug in "parallel parenting" and Search Site.
I'm part of another thread that you might want to check out about BPD parents and their kids.
https://bpdfamily.com/message_board/index.php?topic=276239.0Raising children is an already difficult job but adding someone with mental health issues into the mix makes it even more difficult... .complicated. The effects on children depends on many factors... .the child's own personality/confidence/self esteem, the parenting styles and skills of each parent, the health of the parents relationship, supportive people outside the family... .really all of the things that come into play raising any child with some special skills and issues around BPD.