AAAH! Holy crap. Mind blown!!! 
Let me explain why. I was starting to write a post that both validated and complicated what you were saying, Jim. Validated because, even though I wrote this draft without using the PSR*, when I pore over my scenes to figure out my element quad, there have been cases where I realized (after pinning it down) that it “happened” to match the parent PSR item for the OS at this point. Recently this happened with both Appraisal and Reappraisal.
However, there were some other scenes that seemed to have element quads from out of the blue, including the example one in my post #2 above. That one is the quad under Rationalization. I had noticed that Rationalization happened to be the RS PSR item at this point, but I thought that was just a fluke, since I thought this was an OS scene. It doesn’t have anything to do with the “messed-up romance” that is the main RS, or any of the other surrogate relationships I’d noticed…
…except now I just realized there is an RS relationship between Mandy and Becca, a kind of “frenemies-enemies” relationship that grows and has a strangely heartfelt resolution. Weird! I never noticed that before! Geez, it even fits the RS Problem of Consider. And this scene ends with the line “I knew we could be friends”. 
How crazy that I identified a whole relationship story because of a scene’s element quad!
Okay, so then I looked at another scene whose element quad seemed “out of the blue” and lo and behold, it matches the MC PSR item of Instinct. Not sure why I didn’t notice that – I was thinking OS but it makes total sense it’s MC.
Thank goodness I knew from experience not to doubt you, Jim, or I wouldn’t have triple-checked what I was saying…
I’ll see what happens as I go forward, I’m guessing as the substories gain steam it will sometimes be tricky to know which storyform a scene “belongs” to, and I only have one substory full storyformed. Still, this is super exciting!!!
* it was during NanoWriMo and I was kind of just flying from scene to scene, and didn’t fully trust the PSR yet as I wasn’t 100% sure on Judgment or Outcome. Though I think by this point I was pretty sure, and could tell that the whole PSR quad felt right, but didn’t know “where I was” in it.