Mendog married St. Brychan AP ANLLACH Brenin Brycheiniog, son of Anlach mac Cormaic UÍ ÉREMÓIN sub-king of Irish Demetae and Marchell FERCH TEWDRIG of Garth Madrun. (St. Brychan AP ANLLACH Brenin Brycheiniog was born about 419 in Brycheiniog, Brecons, Wales.)