Yuck, why so many copies ?
I have not come across a situation that requires this procedure
- but
IMO, you need to save to one common location, on the internal HD. ( say "current - in progress" )
- then use a .bat file to copy that directory to your "other" required locations
( you need only to manage the "in progress" folder to keep the amount of data low to fit on the flash drives
I do recall Microsoft "Briefcase" for syncing folders, see if that suits your situation
Are you aware that Mastercam creates addition files in other areas that are not normally seen ?
ie autosave, timed backup,
Sometimes additional files can be used when creating stock shape, toolpaths etc ( these MUST be available when opening a session )
ie a series of files created/used on one computer, you cannot open the Mastercam file on another without errors
- it would only work if a common save location is used for every file, and the data paths to them would be the same for each computer