You wouldn’t want to stream characters. Streaming actually loads and unloads assets from game, and you wouldn’t want to remove a player’s character from game so that another player wouldn’t see it.
What you’re looking for is replication based on distance from a player, I think. Check out this video tutorial series from one of our developers:
This includes information on how to set whether an actor or event is replicated for a client based on its distance from player.
If you have more questions about how to set that up, please open a new post with your questions as they don’t really fall under topic of level streaming. But if you do, please link to it here so that others with same train of thought as yours can follow along. Thanks!