Have you ever merged another community with yours? Why do you think people do that? Have you seen it work or fail before ? I have merged mine with a competitor back in the day, to combine forces and become better. That was back in the day on ZetaBoards where we couldn't take our database and merge the two forums. So members of the closed / merged forum had to re-register and come to the new board. Which often resulted in them not bothering.