Been working on this exact issue myself. It would be nice to see the "parent course" files when browsing the "child" course file folder.
What we need is a HACK of the index.php file (located in /files/index.php). Bascially we need the hack to allow access to the "parent course" file folder when viewing the files in any related child course. Both novice and advance users would appreciate.
I looked at the index.php code myself, but couldn't see a place to hack (though I am not well versed in php).Any suggestions by others would be most appreciated.
One immediate problem I see with this "Hack" is what would happen in backup/restore when you try to backup course files (the deafult) post Hack. On the surface it looks like this Hack would have you backing up both the child and parent file folders - something you probably don't want?