Complex sentence: Several of the members previously played in the group Virtuocity, and after Virtuocity's breakup some of those members formed a new band based on Tuomas Seppälä's songwriting.
Split into simpler sentences: Several of the members previously played in the group Virtuocity. After Virtuocity's breakup some of those members formed a new band based on Tuomas Seppälä's songwriting.