Complex sentence: Burke's Landed Gentry mentions his wife having a sister named Dorothy Purefoy who married Roger Dudley and was mother to Thomas Dudley, Governor of Massachusetts; however; other sources identify Susanna Thorne as the mother of Thomas, and Susanna's mother as Mary Purefoy.
Split into simpler sentences: Burke's Landed Gentry mentions his wife having a sister named Dorothy Purefoy who married Roger Dudley and was mother to Thomas Dudley, Governor of Massachusetts. However other sources identify Susanna Thorne as the mother of Thomas, and Susanna's mother as Mary Purefoy.