Complex sentence: Margaret was a daughter of Sir Nicholas Loveyne and his second wife, Margaret de Vere who had previously been married to Henry de Beaumont and, after Sir Nicholas death, took Sir John Devereux as her third husband.
Split into simpler sentences: Margaret was a daughter of Sir Nicholas Loveyne and his second wife, Margaret de Vere. Margaret had previously been married to Henry de Beaumont and, after Sir Nicholas death, took Sir John Devereux as her third husband.