I write most of my bands songs, and alot of the music, and I was wondering if it were in a little music book how would it look.

Okay, lets say one of my songs (T-3) is listed in a song book for the CD sleeve. I wrote all the lyrics, All of the Bass Line, and a whole guitar part.
Now we have another guitarist who just made up his own guitar part, so would the credits be-

Lyrics-C.Kimball(Me)
Music- C.Kimball

or

Lyrics-C.Kimball
Music- C.Kimball & A.York

...I was just wondering about this...... Im not really sure how the legal side of this works out.