I figured out a way to combine multiple states into one map using MapsetToolKit v1.77 beta on Windows OS.
1) for each state previously installed, "Select IMG" the *.img directories
2) "Select all" the img files [only need to click this once]
3) "Add -->" the img files [only need to click this once]
4) select ok to remove duplicate .img files [multiple clicks]
5) set some basic parameters: map name and unique family ID
6) check the "Install in Mapsource" option [will update windows registry automatically]
7) click "START" [you'll see a CMD window process all the *.img files]
once finished you'll see the new combined map appear in the "Mapset Installed" pane
Then you may use the new combined map in Mapsource or Basecamp. This is useful if your route spans multiple states. The procedure does not overwrite the original state maps.
1) for each state previously installed, "Select IMG" the *.img directories
2) "Select all" the img files [only need to click this once]
3) "Add -->" the img files [only need to click this once]
4) select ok to remove duplicate .img files [multiple clicks]
5) set some basic parameters: map name and unique family ID
6) check the "Install in Mapsource" option [will update windows registry automatically]
7) click "START" [you'll see a CMD window process all the *.img files]
once finished you'll see the new combined map appear in the "Mapset Installed" pane
Then you may use the new combined map in Mapsource or Basecamp. This is useful if your route spans multiple states. The procedure does not overwrite the original state maps.