I know how to get them from one computer to another, my real question is this:

If my Favorites.mpn file in computer one has 50 patterns in it, and my Favorites.mpn file in my second computer has 100 patterns in it (but 75 of them are different from those in computer 1), if I copy the file from computer 2 and paste it into computer 1, will the copy function erase those patterns in computer 1, or will it only transfer the patterns computer one doesn't have?

Windows will ask you if you want to replace files in a folder when moving them, but I don't know about this format.

Like most of us, I work on two computers, and keeping both computers identically updated with pattern files, etc. is a pain.