Hi there,
I’m still trying to figure out how to populate my city with NPCs. I’d love to customize non-controllable characters, but I’m not quite sure how to do that. When I create additional families in the family menu, they just stay there and never appear in the town. Using cheats lets me change a townie NPC’s appearance, but not their name, gender, or age.
The new experimental feature that allows assigning ZOIs to specific places is promising, but since they’re tied to one location and have limited roles, they don’t show up elsewhere. It would be amazing to generate clients for places like the art gallery or bookshop.
Ideally, inactive families in the family menu could be used as random clients or passers-by, similar to how it works in… well… a certain well-known simulation game. 
That would be a great way to add friends to our ZOIs (characters we don’t necessarily want to control but still want to interact with).