Complex sentence: In 2001, the band regrouped, with Collin Burton replacing Simon Jason Smith on bass, and Dave Odart replacing John Large on drums, and Melanie J. joining them on keyboards/vocals.
Split into simpler sentences: In 2001, the band regrouped, with Collin Burton replacing Simon Jason Smith on bass. And Dave Odart replacing John Large on drums, and Melanie J joining them on keyboards/vocals.