It's not a good idea to involve MapSource to generate new map builds from a reverse engineered BlueChart g2 chart.
Split the initial map to subfiles with GMapTool and then join the subfiles you need in a new mapset. This can be done with the GUI version but it may be easier to adjust if one uses the command line version with script files.
One example to build a sub-set of HEU800X v2012 for just Sweden. The sub-set is called "HEU71*L - Sweden v2012".
- Create the subfiles by splitting the original file. In this example I have the "M:" drive with a "Temp" directory. This also assumes that "gmt" is included in the PATH variable. Otherwise you need a full qualified path for the executable in the scripts.
- List with subfiles to include in the new partial mapset.
- Batch file with commands to execute "gmt" to join the selected subfiles.
- Info result from GMapTool