This would be considered a derivative work?

[aMUSEd]

And while I was making a joke (more or less) with my first answer earlier, the Marley tune would be a derivative work. He’d get a writing credit, as you’ve noted. While he’d officially be listed as an “additional” writer on the copyright registration, whoever wrote out the credits you’ve seen may have just wanted it to appear Marley did more—or they may not have known he should have been listed after the original writer. Even on the Zeppelin tunes where Zeppelin at least credits the original writer(s), they sometimes put that writer’s name last. I don’t think there’s anything legally wrong with that, but I also don’t think it fools—or impresses—anyone.

Just checked in Apple Music he's listed as the sole author (ah if you open up song info Martina is still credited but after Marley)

[planetearth]

Yeah, a lot of streaming services aren't crediting people properly, and that's not surprising. Disappointing, but not surprising. And unfortunately, Apple, Spotify and the rest will take whatever info you give them for the credits, no questions asked, apparently. No one at the streaming services will care enough to fix any errors in the credits. (That's part of the reason Spotify has been sued for so much in the past few years.)

You've probably heard about the overhaul they're trying to do to the whole "credits" system, so that the correct (and proper) credits for pretty much anyone associated with working on the recording are stored in a file's metadata (kind of like IMDB). I don't know how far that's gotten yet, but when it's done, there's also supposed to be a database you'll be able to search to see who was the assistant engineer on Fleetwood Mac's Rumours, for example.

Steve