Hi LeneLu
Is anyone familiar with this concept?
I haven't come across the particulars of the "concept" you mention, but I get the general idea from what you are posting, so lets see if I can help.
"In brief it’s about having the strongest, most unmoving view of the world when in a group of 2 or more people."
Has anyone applied it when dealing with BPDs?
There are times for an unwavering position. I was in a relationship with a girl with BPD, at one point her anger got so intense that after the episode was over and she could calm down I told her: "I need you to be nice to me, no questions asked"
Of course she questioned it, I told her not to argue with me on this. It worked, not once was she "mean" to me after.
she will interpret it as...
In this case the point was not about what she would make of it, its about something I needed us to be clear about and would not "negotiate" with her. I know it sounds like I wasn't taking her into account as much as I could have, but she did know it was an issue, and we've talked about it before being an issue: this was the defining moment, we have to finalize it one way or the other or it will keep eating at us.
She could have said no, and I was ok with that.
We "broke up" again for some other reason, so its not a magic bullet to fix a relationship. Its about setting boundaries that you will not compromise on, not about "who is more stubborn", which brings me to the next scenario:
My dad started our family business, we have long term clients/tenants we have to deal with for years at a time. He's the "resolute and unwavering" type. He would not concede any point, wanted the client to acknowledge his "superior bargaining position" and would impose the rules, which to be fair had been agreed upon in writing before, so he was in his right to demand they be followed to the letter.
It caused a lot of conflicts, clients would do exactly the opposite of what was asked just to spite him, they would drag their feet and delay any action until they were overdue, it caused arguments and even threats of legal action.
My dad couldn't handle it, it caused problems at home, financials were strained and opportunities for "better tenants" missed.
So he handed it over to me.
I hard-balled the most conflicting clients: Either shape up or get out. Two got out, made a huge mess about it (broken pipes, missing items, unpaid bills). One other threatened to leave but he went around me and appealed to my dad; in order not to "lose the client" he overruled me, so I set the terms yet again: I will not be responsible for upkeep (HUGE issue, they'd break it, called us to "repair" it, they'd break it again), you pay it, legal action if you don't. He agreed.
Another conflicting client I actually made a compromise with: he would get a new contract with more favorable terms for us, he would get follow ups on unpaid bills and would get charged extra for any late payments. He mostly followed through, a few hiccups but nothing major like before.
We have been tenant-conflict free for over a year now, my dad struggled with them for close to six years, and some years prior with previous tenants. We still have one problem tenant, but my dad still handles him as a "grandfathered client", he's been around for as long as the business has been running.
So my story so far has been about my own background, now on to how that relates to your situation.
I want to exude strength and confidence. I am confident that I have made the right decision in going nc with her up til now. But, I want her to know that it is not a position that I am going to concede... .I want to control the frame.
Exuding strength is not about having the other person acknowledge it, its about sticking to the consequences of your actions.
In your case, by being unwavering and "projecting" that "power" outwards you are taking the role my father once did. You are correct in the sense that you are entitled to your actions, still the other person could react in the opposite way to show YOU that you will not break THEIR strength.
By taking a milder approach, (not to toot my own horn but) sort of like I did with agreeing to better terms where possible and following up with consequences (actually collecting late fees, following up with bills) even when unforeseeable circumstances arose (dad overruled me, I had no control over that), you could better "control the frame" of the situation: it doesn't have to be "conflict", its a "negotiation", even if you have better bargaining power.
but I feel that is a passive approach
Sometimes the best offense is a good defense
So what if she thinks its fear, as long as you're not afraid it is of little consequence.
... .she will actually feed on
It is true that might happen, "extinction bursts" are a thing. Things might get worse before they get better; by controlling your own actions (keeping no/limited contact like you decided on) instead of trying to get her to do something (get her to acknowledge you are not conceding on this), you get her to work around you instead of you reacting to her shenanigans.
I speak from my own experiences so take that into consideration. Long story I know but hope that helped!