Tried. Didn't work. There are serval interesting configs that are currently missing: all characters template and config, levelitem config, smart item config and map config.

However you can still manage to spawn new characters in your shelter, just for the sake of being funny. Open up visit config and open ''visit'' You will find a list of children items under it. Each one contains one or serval templates of which NPC that comes at your shelter during that visit. You can copy one and paste it onto your dweller set under scenario config. Then you will see that NPC spawned at your shelter. But you can't gain access to control him/ her. They just automatically walk to the door and wait outside.

There is one possible way to make a new dweller with new template. That is creating a new visit event for an assigned template as a dweller. Then you might get a new dweller with new model.I havn't tested it yet. I just surmise it will not work or simply crush the game.