Wolcott believes that this is Owain ap Edwin, as you saw in Madog's curator notes. It's speculation on his part, based on the proximity of the families, and the section of "Achau Brenhinoedd a Thywysogion Cymru" as cited by Bartum in Early Genealogical Tracts -- it says, there, that the mother of Gronwy ap Owain (ap Edwin per ABT 2e) was "Morwyl verch Ydnywain bendew ap Neiniad ap Gawithuoed ap Gwrydr." Thus, Ednowain Bendew was the father-in-law of Owain ap Edwin, and Morwyl (Morfydd) was Owain's wife.
I often will go along with Wolcott, who works with the original MSS and the property documents and the histories to make sense of the Welsh Genealogies -- even Bartrum's work, which is the currently accepted standard source, leaves out generations, thus making chronological hash of the lines sometimes. But I think this is too much speculation to make the jump.
Here is where you can read Wolcott's argument:
I put in the curator's note so that I had a record of Wolcott's different reading, if it came up.
BUT the accepted father of Madog is Ednowain Bendew (but not the first Ednowain Bendew).
Thanks for asking! I get lonely, in the Welsh tree.
I'll go put some of this info in the About section, so that it doesn't get lost again.
It's the abbreviation for the work I cited right before it -- "Achau Brenhinoedd a Thywysogion Cymru."
I had to go find it, myself! One of the things that annoys me about Wolcott is that he takes the MS abbreviations for granted, and doesn't provide a list of them.
It means "Genealogy of the Kings and Princes of Wales," and was published in English in 1961 by P.C. Bartrum. His edition is based, apparently, on a now lost MS.
I love questions. So don't hesitate to ask.