Sibyl de Ferrers Peerage person ID=42690 (1230–1273) Parents Sibyl Marshal William de Ferrers, 5th Earl of Derby Children John de Bohun Siblings Alianore de Ferrers Joan de Ferrers Agnes Ferrers Maud Ferrers Isabel Ferrers Agatha Ferrers Elizabeth Ferrers Robert de Ferrers, 6th Earl of Derby William Ferrers Agnes de Ferrers Joan de Ferrers Partners Sir Frank de Bohun