Complex sentence: The couple's daughter eventually married George Manners, 12th Baron de Rosand, due to the attainder against Anne of York's previous husband, became the heiress to the Exeter estates.
Split into simpler sentences: The couple's daughter eventually married George Manners, 12th Baron de Ros. Due to the attainder against Anne of York's previous husband, the daughter of Anne and Thomas became the heiress to the Exeter estates.