Although CP does not name her, Todd Farmerie states that her name was Mabel.
(4) ?Eustacie? (k) who m. William Gouet III, LORD or MONTMIRAIL and other fiefs in that part of Perche which, at a much later date, became known as Perche-Gouet; who was 2nd but 1st surv. s. and h. of William Gouet II, LORD of Montmirail and Chateau-du-Loir, and (jure matris) of Alluye and Brou, by his wife Eustache, and was b. ante 1080. His elder br. Hugh having d. v.p. he became the heir, and joined with his father and mother Eustache, and his brothers Robert and Matthew, in the foundation of the Priory of St. Gilles des Chateigniers as a cell of Tiron. In 1114, as William Gouet junior (juvenem), he was one of the nobles (optimates) of Theobald, Count of Chartres, whom the Count called in to advise him. In 1116, with his father and mother, he gave judgement in a dispute between the abbey of Marmoutier and Gaston de Brou. He suc. his father, probably about 1117. He has been confused with his father, and with his s. and h., William Gouet IV, with whom the line ended.
(k) R. de Torigny does not name her, and Marx does not try to ascertain her name; nor has it been found in charters. She is called Eustacie by Ramsay, presumably through confusion with her mother-in-law.