Note: This line may or may not have validity as per the followinginformation I received:
"JC.18 gives his wife as Nest, daughter of king Cadell of Powys. She, like Angharad, appears to be a late invention, for reasons which are the same as for Angharad. See SW and the note under Angharad. Since Nest probably never existed, the supposed line of descent through her from the kings of Powys is probably not valid. I follow Patrick Sims-Williams in his excellent article "Historical Need and Literary Narrative: a Caveat from Ninth Century Wales", The Welsh History Review 17 (1994), 1-40 (which is what the source abbreviation "SW" stood for above). Before the arguments in this article convinced me otherwise, I was inclined to accept the alleged marriage of Merfyn to a daughter of Cadell of Powys as being valid, just as many others believed. It was Patrick Sims-Williams who put forward the evidence, and I did was to agree with his conclusions. - Stewart Baldwin (edited), GEN-MEDIEVAL"