He [Eustace FitzJohn] married, 1stly, Beatrice, only daughter and heir of Yves DE VESCY, lord of Alnwick and Malton, by [it is said] "Alda" only daughter and heir of William Tyson, also lord of Alnwick and Malton. She died in childbirth. [Complete Peerage XII/2:272-4, (transcribed by Dave Utzinger)]