Complex sentence: Cummings found fame with Dr. Hook & The Medicine Show, the group he named and co-founded in Union City, New Jersey in 1968, and several members of the Chocolate Papers joined the new group.
Split into simpler sentences: Cummings found fame with Dr. Hook & The Medicine Show, the group he named and co-founded in Union City, New Jersey in 1968. Several members of the Chocolate Papers joined the new group.