The Representative is the character on the user account that created the island. All other user accounts can make a character and play on the island, but can't make decisions or major changes. Only the original character can do that.
Ok, so the representative does not have to be the first user account, just the one that created the island? I'll dig into that AC RE thread to see if anyone RE'd it yet, but that might be possible. Is that the main reason people want multiple islands?