Overview
Isabel daughter of William was the illegitimate daughter of William I of Scotland by a daughter of Robert Avenel. She married Robert III de Brus in 1183; they had no children. After his death in 1191, Isabella was married to Robert de Ros, Baron Ros of Wark. They had the following children:Sir William de Ros.
Sir Robert de Ros, was Chief Justice of the Kings Bench. He married Christian Bertram.
Sir Alexander de Ros, who fathered one child, William, with an unknown wife.
Peter de Ros.
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