Suggestion:
Something similar to Free cities' New Game+ feature that lets you carry over 3-4 slaves from an old save. Doesn't have to keep levels skills, etc, just stuff like name, beauty, hair/eye color/ custom descriptions and stuff. I tend to get attached to characters, and this would help mitigate any major changes that renders old saves buggy.
As an extension but not completely necessary, would be nice to have a system like xcom, where you can add some custom characters into a pool, and make them randomly appear as enemies/in the slave market or something.