Sitric Cáech
An agreement of some sort between the Vikings of Northumbria and the Anglo-Saxons was achieved in 926 when Sitric married a sister of Æthelstan , perhaps Edith of Polesworth . 
<triplet> Æthelstan <subj> Edith of Polesworth <obj> sibling <triplet> Edith of Polesworth <subj> Æthelstan <obj> sibling