I'll add to this that the sites are hardcoded, and from my discussions with the Illwinter staff, it seems that the total number of sites is rather inflexible. I.e. if new sites are to be introduced, something else must be eliminated. The Moss Tower, for example, which was seen in the Faerun maps with earlier versions of Dominions, got axed at some point. Subsequently the map files were changed to reflect this to keep Aglarond conceptually intact.