Complex sentence: Cullum has led the Jim Cullum Jazz Band as a successor group; his sidemen have included Allan Vaché, Brian Ogilvie, Mike Pittsley, Don Mopsick, Evan Christopher, Kenny Rupp, Howard Elkins and John Sheridan.
Split into simpler sentences: Cullum has led the Jim Cullum Jazz Band as a successor group. His band mates have included Allan Vaché, Brian Ogilvie, Mike Pittsley, Don Mopsick, Evan Christopher, Kenny Rupp, Howard Elkins, and John Sheridan.