In the disk menu where you found "copy", there are other choices like "Move" and "New Folder".

I you want to move a reg that is already in your single reg's, go into to Disk and point to the file, hit disk menu, press enter. You will see the blue dot, and can now choose your operation. If you want to make a new folder, choose and name that and then "Move" them to your new folder.

The reason I said to put them in "Single Registration" first is because of Ketron It. instructions. Maybe you can move them to a new folder directly, try it.