The Christopher Moresby who married Margaret De Tilliol I believe died in 1443/44
Margaret's second husband and widower Thomas Crakenthorpe died at Towton in 1461 (maybe they have taken the step fathers death date in error?.
Margaret died in 1460? but her will? 5/8/1458 she is still called Margaret Moresby widow(though she was not strictly speaking.
I am still of the thinking she could be the mother of Margaret the Illegitimate daughter of Richard Neville Earl of Warwick who married Lancelot Threlkeld II causing much confusion in her tangled relatioships to this family( well it is a possibility). I think there could be a big enough gap between her 1st husbands death and the second marriage which i have not found the date of. Margaret Neville was born mid to late 1440's