Oman notes:
KINSHIP: Conflict/Error> Dwnn's 'Heraldic Visitations of Wales' volume 2 page 112 inserts an extra generation between Madog and Iorwerth called Dafydd.
KINSHIP: Conflict/Error> Griffith's 'Pedigrees of Anglesey and Carnarvonshire Families' page 26 gives him the wrong father.
KINSHIP: Conflict/Error> Lloyd's 'History of the Princes, the Lords Marcher and the Ancient Nobility of Powys Fadog' volume 6 page 17 makes him the son of Dafydd ap Gruffudd ab Owain "Brogyntyn".
KINSHIP: Conflict/Error> Griffith's 'Pedigrees of Anglesey and Carnarvonshire Families' page 223 makes him the father of his 2nd great granddaughters, Angharad, Margred, and Lleucu.