https://en.wikipedia.org/wiki/Herleva

Herleva also known as Herleve,[1] Arlette,[2] Arletta[3] and Arlotte,[4] and Harlette had three sons – William I of England, who was fathered by Robert I, Duke of Normandy, and Odo of Bayeux and Robert, Count of Mortain, who were both fathered by Herluin de Conteville. All became prominent in William's realm.

Mistress : HERLEVE [Arlette], daughter of FULBERT [de Falaise] & his wife Doda [Duwa] ---. Guillaume de Jumièges names "Herlève fille le Fulbert valet de chamber du duc" as mother of Duke Guillaume II, recording that "un certain Herluin, brave chevalier, prit Herlève pour femme" after the death of Duke Robert[199]. Orderic Vitalis calls her "Duke Robert's concubine", and records her marriage, referring to her husband as stepfather to Duke Guillaume[200]. The Chronicle of Alberic de Trois-Fontaines refers to the mother of Duke Guillaume as "filia…Herbertus pelliparius et uxor eius Doda sive Duwa", specifying that they were from Chaumont in the diocese of Liège but moved to Falaise but that others said they were from Huy, and refers to her marriage to "Herlewino de Vado comitis"[201].