Thank you, Glenn. This would have been very helpful if I wanted to import more files into Organizer. Unfortunately the 60K files are already catalogued and tagged in Organizer so importing I don't think will help.
Maybe I didn't make clear enough in my question that I want to MOVE a hierarchy of folders (folders, subfolders and sub-subfolders) UP to Dropbox without PSE Organizer losing track of their location. To a naive user like me, it looks as if all I have to do is use the MOVE command in the File menu but I've learned to be cautious when asking PSE to do major stuff.