I like the family and find it encouraging that they want to get her help, but I really do not know if it is my place anymore as I have no relationship, friendship or otherwise, with this girl (nor do I want one).
Yes. You know the right answer. It's not your place anymore. And even if you were with her, it still wouldn't be your place. It's her decision.
Do you suppose the motives of the family are to spread the weight of obligation around? Do you suppose the motives of your ex-girlfriend are to keep people obligated? This is the regressive nature of Borderline personality disorder. Most Borderlines are forced into therapy by others. They rarely stop and say, "it must be my issues." That's because Borderlines are defensive by nature due to poor ego development. This is a developmental disorder- poor ego functions and very faint boundaries because of the part time selves.
James Masterson once wrote that Borderlines rarely want to get better. He claimed the of all of his Borderline patients, only 5% truly wanted to admit themselves to therapy and do the work needed. The other 95% were there for the rewarding half of being a Borderline. "The hidden agenda is to get the therapist to resonate with their need to be rewarded and supported and to serve as a new caretaker for them, so they will get the emotional supplies they wish they had gotten earlier in life." ~ Masterson
This is an attachment. Since Borderlines are part time selves, they resonate with mirroring others for their part time halves. A therapist (or any person for that matter) that resonates with fixing, rescuing and responding codes gives the Borderline a blueprint to behave regressively. If the therapist isn't smart about this- the therapy will no longer be effective. The family will be spending money in effect for an expensive friend that babysits and allows the regressive behavior to continue.
Confronting this regression and putting boundaries in place (getting better in therapy) involves getting depressed. It involves an abandonment depression (who am I? no one loves me, no one needs me, I am so all alone, etc.) Borderlines sometimes fight to the death on this. Borderlines will not be comfortable being alone without suffering immense anxiety. They will act out to get others to respond. They want to be taken care of. They want people to help them "feel good" about themselves. The closer they get to abandonment depression, the more they act out in regressive, infantile ways to keep people close. Save me! Any withdrawal by the rescuer is seen as Borderline failure to be whole and the Borderline discharges the angry tension that they feel in clinging. This is called a "rapproachment crisis." In looking at the notes of Borderlines in therapy- this crisis often happens after years of therapy, when the Borderline is feeling better and the therapist suggests that they are able to be alone now and end therapy.
The other hidden agenda that Borderlines have in therapy is to lure others (and the therapist) into resonating with the negative images they have of their parents- This internalized image of their punitive parent lives intrapsychically and condemns the Borderline adult for their self actualization. The fear and rage of self actualization often shape shifts and is projected upon others; perhaps it's people on the sidelines- the ex-boyfriend (you) siblings, etc. -whoever is in line of fire is now the perceived cause of their pain. Since Borderlines cast blame in order to prevent shame- It's important that the therapist realizes that this anger "fantasy world" of bad people only prevents the reality testing of abandonment depression while allowing for a split to take place in the Borderline's part time half as a good object. That part time half lives in fear of the outside World. The all or none thinking of good versus bad has to be confronted by the therapist with the encouragement of ideas that strive for wholeness without others to attach to and to allow for grey areas in people as well as the self.
If all of this sounds like a monumental task- it is. The worst thing you can do as an onlooker is to stand-by and hope for a good outcome. The equivalent of that is watching a pot on low heat come to a boil on the stove. You'll want to ask questions of something that has no answers. It's all in the Borderlines distorted belief which changes with the swinging pendulum, back and forth, back and forth. The movement is what makes the disorder so tricky to pin point. It's the hope in therapy that the pendulum will stop swinging wildly back and forth.
The best thing you can do right now is to allow yourself some distance. Tell the family that your ex-girlfriend needs to make her own decisions- they may be surprised that you are even suggesting that. Her acting out behaviors will occur, but you'll expect them and you'll be prepared. Begin to protect yourself by looking away and focusing on your own therapy. Your own depression will occur and you'll feel badly, but that's to be expected too. Remember, when you're going through Hell, keep going ~ Winston Churchill Good luck.