Is it possible to assign additional unrest for certain cultures, that disappear when a certain province is captured? Something like the pyramids in Vanilla, but generalised and applicable to any culture. Using hidden resources instead of cultures would also be OK, as long as there is unrest which disappears with the capture of a specific province. I would imagine it would involve scripting of some kind if it's at all possible, hence my directing the question at you.

What I am thinking of is adding extra unrest to Gallic provinces, that disappear when the province approximating to Wales is captured, thus simulating the effect of the druids on Celtic independence.