'William Sumner, of Bicester, (brother of Roger, the elder, and mentioned in his will below,) ... was buried 18th March 1596-7.'
The mention in the will is "I doe give and bequeath unto my brother Willm Sumner, his Children, being five of them, ..." The phrase "Willm Sumner, his Children" apparently is the equivalent of the modern "William Sumner's children", because William himself died several years before this will was written.