You don’t need to download your entire custom song library again to add them to Your Collection. Please don’t do that.
Instead visit the Author’s Directory.
1. Open an author’s profile page in a new tab.
2. On the right side of the screen you’ll see their song list.
On the far right of each song is a button marked ‘Collection add/remove’.
3. Click this button!
You will have to cross-reference the customs database and the authors directory yourself. This should be MUCH faster than trying to download thousands of individual custom files.
Have fun!
Keeping the content Canadian since 2017!
SomeOldGuys: https://db.c3universe.com/songs/all/__user/someoldguys
MrPrezident: https://db.c3universe.com/songs/all/__user/MrPrezident