Margaret of Brittany
He was also childless , and to avoid any subsequent dispute , he arranged the marriage of Margaret to his first cousin , Francis of Étampes , the second in the order of succession and the last male left of the Breton House of Montfort; also , he arranged the marriage of the younger sister Marie to John II , Viscount of Rohan , the most powerful noble in Brittany . 
<triplet> Francis of Étampes <subj> House of Montfort <obj> family