Amongst his many descendants we find the Dukes of Ursel .
They are considered to be the founders of the Flemish branch of the house and became owner of the castle and lands in Billy in the County of Artois south of Lille .
Amongst Billy 's many descendants we find the Dukes of Ursel .
They are considered to be the founders of the Flemish branch of the house and became owner of the castle and lands in Billy in the County of Artois south of Lille .