Ok.
Bartrum calls first wife Gwenllian -- Wolcott disagrees. Whatever manuscripts Bartrum is using for Gwenllian he doesn't say -- he gives John Lloyd's History of Wales as the source for her death date.
I wish to high heaven Dwnn gave the mss that he's using, but no, can't have that. At any rate.
His entry on page 69 gives Annes ferch Rhys -- the same father as Gwenllian's, different name.
As you note, Steven, his entry on page 99 specifies Gwenllian as the wife of both Rhodri and Ednyfed Fychan -- no knowing what manuscript this either, though it's been checked by William Hughes and J. Davies. Whoever they are.
Cawley gives this wife as Nest, same family, different name. And says that there are no primary sources to confirm, which isn't exactly true, since Bartrum and Dwnn are both working from manuscripts, unnamed alas. And which contradict each other, as don't they often.
But where Cawley is getting the name Nest is totally unclear, since he cites no secondary sources and says there are no primary ones.
(I very rarely -- well, never, really -- look at Cawley for the Welsh; he's good, very good, but he's not clear on Welsh sources.)
Ok.
So we look at what Wolcott is saying:
"6. Gwenllian ferch Lord Rhys, born c. 1180. She married Ednyfed Fychan (c. 1165) the seneschal of Llewelyn Fawr of Gwynedd. Her death is recorded in 1236[17]. Most sources claim she also married Rhodri ap Owain Gwynedd, but we believe that was a different lady whose name was probably Annes. (see below)"
and
"24. Annes, born c. 1174. According to Gerald of Wales, when he met Rhodri ap Owain Gwynedd in 1188, "only a short time before Rhodri had taken the daughter of Prince Rhys as his mistress". Gerald did not name the lady[44]. Some medieval genealogists[45] say it was Gwenllian ferch Lord Rhys and that she was married to Rhodri before she married Ednyfed Fychan. We suggest Gwenllian, who married Ednyfed Fychan about 1195, was under 10 years of age in 1188 and would prefer the source which calls the mistress of Rhodri "Annes"[46]. And we suspect Rhodri, born c. 1135, already had sons her age in 1188, by an unknown wife. One source, which calls this daughter "Gwenllian", says she was the "graig" (wife) of Cynan ap Rhodri[47]. While that is chronologically impossible, she may have been the mother of Cynan.[48] "
That Giraldus Cambrensis says that the woman we are talking about was a mistress and not a wife is something I discount, because 1) Bartrum labels this a marriage and 2) in the section where Giraldus is describing Rhodri and his household, he's both annoyed that none of Rhodri's household took the cross, and also refers to Rhodri's wife as illicitly married to him, since they were cousins.
The Welsh not only didn't care about illegitimacy, they didn't care about degrees of relationship. (They were first cousins once removed, is what.)
So I think we can infer that indeed this was a wife. Giraldus goes up my nose.
Allrighty then!
Where are we --
Here is what I would do -- the children belong to a mother who is the daughter of Rhys ap Tudur. She is not her half sister Gwenllian, who married Ednyfed Fychan.
Her name is not Nest; dunno where that came from.
So, yes, I would agree with Wolcott, that her name is Annes, EXCEPT shse was a wife, not a partner.