That Owain Glyndŵr had another brother Gruffudd is likely; that he possibly had a third, Maredudd, is suggested by one reference.
Det er desuden sandsynligt, at Owain Glyndwr havde yderligere en bror ved navn Gruffudd; muligheden for at han havde en tredje bror, Maredudd, bliver nævnt af en enkelt kilde.