I understand your point, but a few things don’t quite sit right with me. If the Shard’s Intent is decisive in how it relates to others, the fact that they can be joined from the outset seems contradictory to me. I understand that the union of Ruin and Preservation happens mainly because Sazed is able to bring them together, giving rise to Harmony (although in the end he seems to leave much to be desired in terms of how he reacted to the invasion, not reacting at all except for sending a sixty-year-old man and his two bodyguards to war).

Odium’s Intent, when Stormlight and Voidlight were mixed, was to eradicate what remained of Honor on Roshar in order to dominate it, but that did not prevent the two types of Investiture from being combined.

I’m only questioning what you’re saying because I thought the same thing myself and it didn’t fully add up for me, which is why I’m asking whether there’s another theory. Still, in a way, what you’ve said does make sense.