Complex sentence: Though not yet a member of the Grateful Dead, T.C. played prepared piano on the group's second album, "Anthem of the Sun", and formally joined them in November 1968, to supplement Ron "Pigpen" McKernan's organ playing.
Split into simpler sentences: Though not yet a member of the Grateful Dead, T.C. played prepared piano on the group's second album, "Anthem of the Sun". He formally joined the the band in November 1968, to supplement Ron "Pigpen" McKernan's organ playing.