We have changed the rules to edit songs already available in the DB, the announcement has been updated accordingly.
Upcycled customs: Any song posted by an author in the DB and reposted by another author with marginal edits. If you see a song in the DB that is missing an instrument or 2, contact the original author and contribute to that version. If the author is not willing to collaborate, start authoring the song from scratch if you want it released. If the author is unreachable or if you think there are special circumstances (like very very badly authoring of the original version from which you would start anyway to save time, for example), contact a moderator. If your edits are substantial (you are making a drums only song full band, for example), always contact the original author if the song is in the DB but in this case you can upcycle without permission for the benefit of the community: make sure the original author is properly credited. Upcycling without permission is stealing stats and recognition, which is what fuels the community of authors, and we can't allow that by any means.
We understand that C3 Universe is giving authors some added motivation with all the stats available, and that is exactly why I came up with the concept. However, authors should be the first one to understand how time consuming it is to author a song and that collaborations are only a small part of the effort and should not take away from the songs already posted in the DB. If you want to update a song, do it and send your upgrade to the original author who will credit you. No, you won't get stats for that, not yet anyway (maybe in the future if I find the time to wrap my head around how to do it), but it doesn't matter, that's the proper way to do it. If you want to be the original author take a song not in RB3 format yet and work on that, or start from scratch. If the original author is really absolutely not responding or they're behaving in a way you think is wrong for the community, contact a moderator to discuss it. Otherwise don't appropriate other people's work because you did some cool venue effect or because you added keys: as an auhor you should know way better than this.