Thanks so much!! William is a Wonderful WikiTree collaborator!
He resolved a "disputed parent" issue with Maud (de Vaux) de Ros by finding additional information and posting [this comment] to her profile.
William's comment provided a link to a post by Douglas Richardson in soc.gen.medieval correcting the mother for Maud published in Royal Ancestry. It is a detailed and interesting discussion, with the bottom line:
Inasmuch as Joan de Peleville, 1st wife of Sir John de Vaux, must have died sometime between 1250 and 1254, she obviously can not be Sir John's wife who was the mother of his two daughters, Pernel and Maud, both of whom were born after 1254. That leaves Sir John's surviving wife, Sibyl, as the candidate to be the mother of the Vaux girls.