I know this is quite an old post but maybe it will help somebody. I have figured out how to bring the character back. (In my case it was the keeper)
Go to your save and find your character, then find their coordinates+rotation, and replace them with the desired ones (you can get them from another character or from an old save) then find the old ones in the save again and replace those too. (Keep in mind that i did not try it for servants.) If you need more details you can ask, there is a non zero chance that i might see it