cities for the Levi'im

A few weeks ago we discussed the dispute between the Rambam and Ra'avad (Shmita 13:11) whether Kohanim and Levi'im receive a portion in lands conquered by the Jewish people outside the boundaries of Eretz Yisrael. The Rambam holds that it is only in Eretz Yisrael that Kohanim and Levi'im cannot receive land, but they would share in other territory. The Ra'avad disagrees and holds that the Kohanim and Levi'im can never receive land because they receive terumos and ma'asros as a substitute.

In last week's parsha we read the mitzvah to set aside 48 cities as homes for the Levi'im. The Minchas Chinuch (mitzvah #408) questions whether there be a mitzvah to set aside additional cities if more land outside Eretz Yisrael is captured. The question raises two issues: 1) Is 48 the minimum number of cities which must be designated, but the total number may increase depending on population and availability of land, or is 48 the total number of cities required? 2) If more cities may (or should) be added as the amount of land governed grows, does this mitzvah to set aside cities apply even to territory in which, according to the Rambam, the Levi'im already receive a portion?

The Sefer haChinuch writes that the cities given to the Levi'im are a substitute for their not receiving their own section of land in Eretz Yisrael, implying that if they did receive an allocation of land, there would be no mitzvah to set aside designated cities. However, according to the Rambam, just like there is still a mitzvah to give Kohanim and Levi'im terumos and ma'asros even though they receive a portion in the expanded territory , so too, perhaps there is also a mitzvah to set aside cities as well.