I have two separate sources for a Robert de Turnham: (1) as father of Beatrice m. Ralph de Fay (Plantagenet Ancestry); (2) as father of Isabel, heir of Robert de Turnham m. Pier de Mauley in c 1214 (CP). I originally had them as the same Robert; however the dates indicate that there are probably 2 different ones; as well as the fact that Isabel is "heir" - not "coheir" of Robert, according to CP. Therefore I have added a 2nd Robert, father of Isabel and son of Robert (who was father of Beatrice). This also allows Isabel to have a birth date of c 1197, which fits well with a marriage date of c 1214 and her parent's marriage date of c 1194-7.
------------------------
Robert de Turnham, who was Steward of Anjou in 1199, and Steward of Poitou in 1204, had m. c 1194/97, Joan, daughter and heir of William Fossard. Piers thus acquired in right of his wife the numerous lands comprising the Fossard fee in Yorkshire, which in 1166 had amounted to 33 1/2 knights' fees. [Complete Peerage VIII:555 note (c)]