Complex sentence: It also included the last two recordings by The Band of new songs credited to pianist Richard Manuel; both were co-written with guitarist Robbie Robertson, who would continue to be the group's dominant lyricist until the group disbanded in 1976.
Split into simpler sentences: It also included Band's last two recordings of new songs credited to pianist Richard Manuel, both co-written with guitarist Robbie Robertson. Robertson would continue to be the group's dominant lyricist until the group disbanded in 1976.