In the aftermath of the Snow Queen's spell, portals were opened up all over Storybrooke bringing in people from realms far and wide - across all universes (even the alternate ones). In a desperate attempt to protect the world at large from the influx of these newcomers, Regina sealed off Storybrooke permanently, making it impossible for anyone to leave the magical town.
The pamphlet said that anyone under the age of eighteen needs to have a guardian twenty-one or older. I'm seventeen, which is actually an adult where I come from Shh, I know I'm still in school, but I did turn seventeen at the beginning of the year, and my eighteen-year-old brother is here. I would really rather live with Ron than some stranger just because my brother is deemed not old enough to care for his grown sister. Is there some sort of exception that can be allowed for certain circumstances?