Whenever someone chiefs an inactive village (ie farm), everyone else is still raiding the village. This leads to various conflicts and frustration, as we know.
I suggest that we borrow a feature from trade routes. When a village (or its owner) changes alliances, all the trade routes to that village disappear. Let's apply the same idea to farm lists: when a village (or its owner) changes alliances, it will be automatically removed from all farm lists.
This will help prevent arguments over defending chiefed villages, and save us the bother of sending igms to all the people farming our new village.