Hmm, good point. How about this:
When you create a composition, it is an Original. Only the author of an Original may make a modification to it. If the author cannot be found, and someone else now holds his or her Original, no more changes to that Original will ever be made.
Anyone who holds an Original may make a Copy. These copies may not be modified, but may be distributed to others. Copies are linked to the Original. If the author makes changes to the Original, those changes will immediately be reflected in all copies that exist.
If you hold an Original that does not belong to you, or if you have a Copy, and you wish to preserve its current state or create your own composition based on it, you may derive a new composition from what you have. This new composition becomes an Original with you as its author. Viewing the history of the composition will show full attribution to authors of all previous compositions including (in-game) dates when the Original and any derivatives were created. There is, and should be, no distinction made based on how much each derivative work is modified.
If you destroy an Original, the copies are not destroyed. Obviously, no more copies will ever be generated, but also those copies will never change because there is no more Original.
When you create a composition, it is an Original. Only the author of an Original may make a modification to it. If the author cannot be found, and someone else now holds his or her Original, no more changes to that Original will ever be made.
Anyone who holds an Original may make a Copy. These copies may not be modified, but may be distributed to others. Copies are linked to the Original. If the author makes changes to the Original, those changes will immediately be reflected in all copies that exist.
If you hold an Original that does not belong to you, or if you have a Copy, and you wish to preserve its current state or create your own composition based on it, you may derive a new composition from what you have. This new composition becomes an Original with you as its author. Viewing the history of the composition will show full attribution to authors of all previous compositions including (in-game) dates when the Original and any derivatives were created. There is, and should be, no distinction made based on how much each derivative work is modified.
If you destroy an Original, the copies are not destroyed. Obviously, no more copies will ever be generated, but also those copies will never change because there is no more Original.