I don't Reddit or Discord, so asking here. Can anyone explain why, pre-unification, lake fed countries get to break the rules about joining wars, or if there's a method to this madness?

I'll hold off on LFs allying-and-joining while a defensive war is in progress, as I assume the alliance isn't occurring through normal diplo (never played LF).

But having a random assortment of other LFs -- who aren't even mentioned as potential combatants -- join as non-co-belligerents immediately after declaring is cheap. (And it is partially random, I save-scummed to check.)

And then some will even jump in months later while I'm mopping up, meaning I now have to fart around requesting and revoking military access a half-dozen times while tromping my armies over to THEIR stuff to smash them about a bit.

Can't fault them; it's a great strat to be maximally annoying while making a war cost more time, resources and hassle than initially expected, with very limited potential benefit to the aggressor.