Robert married Hawise, whose parentage is unclear and had one daughter Gunnora de Valognes, who married, firstly, Durand de Osteilli and, secondly, Robert Fitzwalter, and had issue.
References
Crawford, George. The Lives and Characters, of the Officers of the Crown, and of the State in Scotland: From the Beginning of the Reign of King David I. to the Union of the Two Kingdoms. Collected from Original Charters, Chartularies, Authentick Records, and the Most Approved Histories. Volume 1. Robert Fleming, 1726.