Complex sentence: Her paternal grandparents were Reginald de Braose and Grecia de Briwere, and her maternal grandparents were William Marshal, 1st Earl of Pembroke and Isabel de Clare, 4th Countess of Pembroke, daughter of Strongbow and Aoife of Leinster.
Split into simpler sentences: Her paternal grandparents were Reginald de Braose and Grecia de Briwere. Her maternal grandparents were William Marshal, 1st Earl of Pembroke and Isabel de Clare, 4th Countess of Pembroke, daughter of Strongbow and Aoife of Leinster.