As for how an army could destroy any/all holdings in an occupied land, i
would limit the destruction to 1 holding per unit in the province. I cant see
1 infantry unit destroying several guilds, temples, and law in one fell swoop.
Of course the regents on the other end of the destruction would be forming
whatevery plans they could take to avenge this act, ie. assassination & hire
troops to stop the slaughter.
Also, the troops would have to be non-active to perform these tasks. Troops
guarding the new province's border cant destroy roads, bridges, temples, and
destroy stores and warehouses. I would allow units not involved in a war move
and that have been in the province a turn to do this action. The occupying
Regent might have to use an action to order this, but i haven't decided to
use this rule in my campaign.

any thoughts?