yeah it is all about the deal that you agree upon. My original band I wrote 99% of the songs however I did give credit to members contributions if they were important in the songs major appeal such as a signature lead lick, or some hook that took it to the next level. I always believed give credit where credit is due. People always perform better when they feel their contribution is recognized.
Agree^ The singer/songwriter in our band did not want all the credit and even said the bandmates parts that they wrote brought life to his songs.
There is one song on the album that I did allot of work on that brought the song to life. Another song he brought us I tuned around 360 degrees from what he was thinking when he wrote it with a simple bass line. It improved the song so why not get musical credit?