Joan (Thwaites) Copley - Disputed parents (ancestry of HRH Prince Charles)

What won’t help is the will of John of Lofthouse in 1462, he only mentioned his unmarried (at that time) daughter.

Joan is not shown as his daughter in this study

https://williamhenryfluen.de.tl/William-Thwaites.htm

She is listed as his daughter in Magna Carta Ancestry

Douglas Richardson, Magna Carta Ancestry, 2nd Edition, Vol. II, p. 446. [https://books.google.com/books?id=8JcbV309c5UC&lpg=RA1-PA446&am... link] Joan Thwaites, wife of Lionel Copley, mother of John Copley b 1444, Daughter of John Thwaites, of Lofthouse [no mother listed]

If her child was born 1444, she was born no later than 1427, so a daughter of Joan Thornton.

Isabel Thwaites is in the wrong generation.

"John Thwaites of Lund and Denton was married twice, 1st to Jane Thornton, and second, about 1439, to Isabel Ryther, sister of Sir William Ryther of Harewood Castle, knight; she was one of the two co heirs to Harewood Manor, and the grand daughter of Sir William Ryther, Kt. and Sibyl (Aldeburgh) Ryther"

She married about 1439 to John Thwaites, of Lofthouse and Denton And it looks like she died in 1484.

Who were her parents ?

https://books.google.com/books?id=8JcbV309c5UC&lpg=RA1-PA446&am... has

William Ryther & Sybil de Aldbugh
William Ryther b 1379 & Maud Umfraville
William Ryther b 1405 & Isabel Gascoigne; Gilbert

So Isabel should be in the 3rd William generation

http://our-royal-titled-noble-and-commoner-ancestors.com/p1054.htm#... has

Sir William Ryther, Sheriff of Yorkshire & Lincolnshire was born circa 1379 at of Ryther, Harewood, & Scarecrot, Yorkshire, England; Age 30+ in 1435, age 60 in 1439. More likely, he was 50+ in 1435.6,3,5 He married Maud Umfreville, daughter of Sir Thomas Umfraville, 5th Lord Umfraville, Sheriff of Northumberland, Captain of Roxburgh Castle and Agnes Grey, circa 1400; They had 2 sons (Sir William; & Gilbert).6,2,3,4,5 Sir William Ryther, Sheriff of Yorkshire & Lincolnshire died on 1 October 1440.3,5

And places Isabel as their daughter.

She's a co heir of the manor, why wasn't Gilbert of Alford Wells?