Actually, in the RPG, the way that the Lights are able to do the thing with their Choirs is that there's a Lesser Magic spell called Link, which appropriately enough links users of the same Lore. It's also noted to be particularly difficult as far as Lesser Magic goes, and only known by the Order of Light and some Ulrican temples.
Just because this is Lesser Magic doesn't mean other Lores could learn it - Hysh in particular has very heavy associations with harmony, and everyone knows that wolves hunt in packs so it makes sense that some Ulricans know how to do this.
Maaaybe the Jades could learn it, given their associations with growth and possibly if you apply a metaphor along the lines of 'you cant have a forest without individual trees', but I have a hard time seeing the other Winds as capable of managing it. And a multi-Wind version feels right out.
IIRC Boney said that it happened at some point after we arrived and that Kadon 'crushed it'. He is really good at what he does.