I'm not an IP lawyer, but I have a handful of patents. As a patent lawyer explained to me, the list of inventors on a patent should be strictly based on whether somebody actually invented something or not. It's not like an academic paper, where everybody on the team gets to be an "author."

In my view the same thing should apply to songwriting. The current standard is, you wrote a song if you wrote the melody or the words. Sometimes those are two different people.

If you added value in other ways, add your name to some other contract specifying distribution of proceeds.

The songwriting is extremely valuable, otherwise just write your own damn songs.

As an aside, "inherent value" is a mushy concept that seems to defy any meaningful description.