Complex sentence: Former Temptation Theo Peoples joined the group in 1998 becoming the lead vocalist as Levi Stubbs fell ill with Ronnie McNair taking Payton's place.
Split into simpler sentences: Former Temptation Theo Peoples joined the group in 1998. Peoples soon became the lead vocalist, as Levi Stubbs fell ill, and Ronnie McNair took Payton's place.