Complex sentence: It belongs to the Order of the Cistercians of the Strict Observance (which has about 35 members), and is the mother house of the Cistercian family, which owes its name to that of the abbey.
Split into simpler sentences: It belongs to the Order of the Cistercians of the Strict Observance. The abbey has about 35 members, and is the mother house of the Cistercian family, which owes its name to that of the abbey.