by Colin Fraser.
As always, Ken provides good advice, but I would add to that, as a precaution, back up the new course, but in two or three parts. Make each part smaller, then move them to another location, along with a copy of the original. Once there, add in a text file describing what's in each .mbz file, where it's from etc, then put three new backups with the text file into a single zipped file. Yes is additional work, but it is precautionary. Whenever I've done something similar, I try to make each package about the same size, keeps it cleaner for me, easier to track with a descriptive text file and much easier to restore.