About Marchell verch Tewdrig
See Peter Bartrum, http://cadair.aber.ac.uk/dspace/bitstream/handle/2160/6516/TABLES%20-%20EARLY%20SERIES_27.png?sequence=19&isAllowed=y (November 9, 2017; Anne Brannen, curator)
born: 379 or 403
Marchell ferch Tewdrig was born circa 430 at of Garthmadrun, Brycheiniog, Breconshire, Wales, England.1 She married Anlach mac Coronac, son of Coronac mac Eurbre "Wyddel", circa 456.
Please see Darrell Wolcott: Another Look at Teithfallt of Gwent; http://www.ancientwalesstudies.org/id168.html; in which he provides the correct father for Marchel. He was not Tewdrig of Gwent, but an earlier Tewdrig :
"These are clearly names of Gothic, not Celtic origin, which have merely been rendered in the Welsh style. Tewdrig was derived from Theodoric, and Teithfallt from Thiudebalth. In the Brychan pedigrees, men of those names are said to have descended from a Greek man called Annhun Ddu or "Antonius the black" whom we suggest came to Britain (or at least his son did) about 300 AD. Likely a Roman military officer, this "Teudfall filius Annhun" married the heiress of Garthmadryn  and was the ancestor of Brychan for whom the lands were renamed Brychieniog. Around the year 355, that family produced our first known "Theodoric ap Thiudebalth", the father of an heiress named Marchel...mother of Brychan. In our search for another Roman soldier called Thiudebalth who 100 years later also might have named a son Theodoric, we turn to Roman history." (Steven Ferry, April 11,2017.)