In general, being able to transfer a city from 1 player to another without requiring the whole revolt/conquest process, and maybe inheriting the farm villages, as long as both players agree would be nice. Of course, there is the risk of a player being forced to give up a city by a larger player. Also, what happens if the city is in revolt? Does the revolt continue, or is it ended prematurely? Probably all of the units disband, but does support stay, or is it automatically returned? Is there a cooling off period? I could see this being used to pass a city in revolt to a small player to get the morale advantage, and then passing back after revolt is over.
I know, all I seem to do is find ways that suggestions would be misused. But I'm really trying to just make sure things are thought through, not just trying to shoot everything down.
Maybe morale stays the same as it was before the hand off?