So I've been experimenting with this but I need some help. What I did is backed up both saves using JKSV. On my original save (Where my character is the island representative), I renamed the folder in the backup folder from Villager0 to Villager1, and copied this Villager1 folder to the save I would like to import my character into. I had a dummy account on that save (also Villager1) so I deleted that folder and replaced it with my own Villager1 folder. I then launched NHSE to change the Island name from my former island's name to the new one in the save I am trying to import my villager into. Success! My character was now on the new island, replacing my dummy character and leaving that island's representative (Villager0) alone.
Only problem I've run into is that I cannot check the mailbox of my house - the screen just kinda blinks and nothing happens (But the game knows it's my house because I can move/edit furniture inside it). Second - I cannot use my axe or shovel, it states only "best friends" can do this. Third- all villagers seem to think I'm a visitor. Does anyone know how I can modify my villager to completely be marked as native to this new island? Perhaps...somehow injecting my villager without modifying any of the flags could do it? (But how?)