Hello Matthew,  I, personally, would solve the problem of using both
names by simply putting them as Offenbach/Holcomb, the first name being
the composer, the second the lyricist.

It shouldn't take up too much room on the label that way and yet will
give their names.  If you are doing it on-line with links their names
could be used to link to more information on each of them.

Just my two cents,

Kelly Goodman - Gnaw-Vol-ty Music Rolls
http://Gnaw-Vol-ty.com/