In the family of "David de Malpas" is listed (from his first marriage) "William de Malpas" who married "Margery, daughter of Cadogan de Lynton, s. p. [without issue]" and also had illegitimate children (including nine daughters, names not given) with "Beatrix de Montalt."
"Beatrix, dau of Rob. de Montalt, seneschal of the earl of Chester" had illegitimate children (2 sons and 9 daughters) by "William de Malpas, son and heir [of David de Malpas], died without legitimate issue."
In the family of "Robert de Montalt, seneschal of Chester ..." is listed "Beatrix, concubine of William, baron of Malpas, and mother of David the Bastard."