OK, I guess I (maybe I'm not the only one) miss an important piece of information here. Let's say I have this "Outside" box set which is made of Releases "Inside" and "Inside (the Sequel)". I intentionally used the word "Release" because there are other Releases of "Inside". I know which Release of Inside is included, because of it's bar code. How am I supposed to enter this box set? I guess I'll create a new Release & RG for the box set. But will I have to enter the track lists of the included albums? Or will I only use the new relationship and the UI will automatically copy the isolated Releases inside my new box set?
If I must enter the track list, then maybe the RG-Release is unnecessary. Anyone can guess the Release from the track list. There would still be ambiguities, for example Releases with "explicit" versions, but these maybe don't matter. But if a user wants to indicate a specific Release, I think we should allow him to.
But if the box set track list is automatically copied from existing Releases, I don't see how we can avoid going to the Release level.
So how is this going to work?