I think I need to find/create a whole country map then import these cities' cache to it. See collaborative cache at:http://help.arcgis.com/en/arcgisserver/10.0/help/arcgis_server_dotnet_help/index.html#//009300000078...I tried this method for a world map: removed world map's cache, imported two cities' cache to it. But then world map's zoom levels are gone, (can't zoom out to see two cities at the same time). If I can't find a better method, i will use this.