Keats-Rohan vs Medieval Lands

Keats-Rohan (Domesday Descendants, p. 746) says that Robert was "Norman, from Trvires, Calvados, given the barony of Burgh by Sands, Cumberland, by Henry I (Sanders, [English Baronies,] 23). He married a sister of Ranulf of Chester. She then adds that his heir was his daughter Ibria, wife of Ranulf Engaine of Idsell, Cumberland - Ibria and her son William Engaine both being dead by 1158, when their heir was William's daughter Ada, wife of Simon de Morville (d. 1167).

According to FMG's 24 Mar 2022 update,

Ranulph / Ranulf I de Bayeux, Vicomte du Bessin had one child: Ranulph / Ranulf II, Earl of Chester. FMG further shows that his son, Ranulf du Bessin "le Meschin", had three children. Robert de Trivers does not show as a husband.

Ranulf "de Gernon", Earl of Chester (b. bef. 1100 - murdered 16 Dec 1153) -- √ Brother of Alice ... Agnes (b. [1098/1105]) -- Earl of Chester. Agnes m. Robert de Grantmesnil -- √ Sister of Ranulf,
Alice (? - after 1139) -- m. 1st: Richard FitzGilbert de Clare; m. 2nd: Roger de Condé -- √ Sister of Ranulf