Breaking the BPD Cycle

[strugglingBF]

My uBPDgf currently live in separate houses.  She has two kids from a previous marriage (20f and 18m) and I have two kids from a previous marriage (12f and 14m).  I suspect her daughter of being BPD and narcissistic as well.  So I am constantly working with a GF (BPD), who is constantly dealing with a possible BPD and narcissist daughter.  This seems to have a compounding effect on my relationship with GF, because her daughter is always creating some kind of chaos in her home, life, etc.  When things are not going well in my GF's house, they typically do not seem to go well for my relationship.  At the very least, I feel like my GF is usually only one small irritation away from a BPD-related behavior of some sort.

I am looking for some advice on this dynamic.  Has anyone ever experienced a similar situation with a spouse and their child both being BPD?  Any advice? 

BTW...I have zero belief that GF's daughter is anywhere close to moving out and supporting herself.  Even if she does, I fear she will be in and out of my GF's house for a very long period of time.  She does not have the maturity or life skills (budgeting, paying bills, etc.) to make it on her own long term.

[RELATIONSHIP PROBLEM SOLVING]

RELATIONSHIP PROBLEM SOLVING This is a high level discussion board for solving ongoing, day-to-day relationship conflicts. Members are welcomed to express frustration but must seek constructive solutions to problems. This is not a place for relationship "stay" or "leave" discussions. Please read the specific guidelines for this group.