I am an attorney. NOt just an attorney but an attorney involved in entertainment law, a musician and, as it happens and fan of this site.
You must understand that a copyright filing is merely evidentiary. As soon as someone writes material, they own the copyright. Property ownership is generally defined in legal terms as a bundle of rights. There are many different ways to exercise rights and in various contexts that have diferent meanings, implications and applications.
Now, to step from the theorectical for a moment, you should consider his contribution "work for hire". Pay the man a flat fee and get a release. You will be able to do this by telling him that, in fact, it was work for hire. the release will protect you against future litigation should the music make money.
Tell the man this. At this point, he will be the only one in the plus category. However, becuase he was engaged with the other working together in a particular time for a particular purpose, that is, the completion of the recording, there is ample grounds for the claim of work for hire anyway. This is important. If the man does not want ot sing the release, he gets no money, and, you will ultimately claim it is work for hire anyway. Unless he is certain that his share will be worth more than about $50,000.00, litigation may be cost prohibitaive. To be sure, the threate of litigation is a none to appealing prospect for the band either since it could easily wipe out any profits generated by the album. But the most important fact is that you stand a good chance of being able to win ont he work for hire basis in which case his share of the profits would be negligible.
You should be fair and pay a fair rate for two reasons. First, there is a moral responsibility eluded to by someone else herein and secondly, if you pay a B.S. amount, he will be able to claim the the payment was a sham to try and make it look like work for hire when in fact it was not. By trying to under pay you stand the chance by biasing a court in his favor and pushing a borderline decision on the work for hire issue in his favor. Be careful on this one. Court is not the place you want to end up it at all avoidable. Just becaus you may have a strong legal position does not mean it will not cost a fortune establishing your rights.
Hope this was helpful.
If you need further assitance, please feel free to e-mail me at either
JWLAWPI@AOL.COM or
JWEINSTEIN8@RR.NYC.