The Sims game should have the option to make some members in a household NPC. Think about it.
With the option of changing a member of the household to NPC or from NPC would allow the player to focus on the story line of some individuals while then back to the others when the player is ready to...
We already have them, the dogs & cats. One of the big complaints was that they were not controlable or even able to look at data. Why expand the problem?