Reading over the last few posts, and mulling it over some more, I think what would have made the most sense is if the Rey/Kylo connection was very explicitly established in TFA. Something like, Rey senses Kylo when he arrives on Jakku, and she sets off intentionally looking for BB-8. Then Snoke plays on that innate connection in TLJ, and it all comes to a head in TROS, where their connection becomes so powerful that they can teleport lightsabers to each other like it’s nothing.
The problem is, J.J. hadn’t thought of the Dyad in TFA (or at least, he didn’t make it clear). So Rian comes in and artificially creates a connection between the two of them (a connection which they even question, like, “Wtf what’s happening?”) as a tool for character building, not a grandiose plot point. Then J.J. comes back and says, “Nah, that was a ‘Dyad’ all along! DYAD!!” I can’t see a way of making it work without A) Doing massive recuts to both TFA and TLJ, and B) Finding new scenes for TFA that never would have been filmed.
If I can get it to work, I think “becoming a Dyad” is the most elegant solution, something that’s vague enough to appeal to both sides of the aisle. I was playing with it more on my lunch break…I should be able to post a second attempt later this evening.
I agree with literally everything here. Nothing much else to add here.
On the topic of your B) point, I already mentioned the “It is you” Kylo line when Rey grabs the lightsaber. I feel that would possibly hint at such a connection in TFA, but it probably isn’t enough. Like you said, it would probably have to be entire scenes in order to be clear enough.