Angeletta is the daughter of Simeon. John is the son of Isaiah. Simeon & Isaiah are brothers. I have spoken with two of Angeletta & John's granddaughters (children of Nevada Neal). They confirm that John & Angeletta were first cousins (which is further proof that Simeon & Isaiah are brothers).
Regarding Nancy Williford: She was born 1797 in SC and died circa 1883 in Leslie County KY. She is a widow living with son Richard at the 1880 census (Leslie). A series of deeds transferring the property of Simeon Wilson appear starting 1884 in Harlan and Leslie County. It seems likely that the property remained in Nancy’s hands until her death. Nancy is presumed to be the daughter of John Williford (b 1761-1765 d 1834) and Elizabeth (b 1766-1770 d after 1836), based on his consistent proximity to John and Richard Wilson in early Knox/Harlan. He first appears on Knox tax lists in 1804 and appears there until his death in 1834. (John Williford last appears on Harlan tax lists 1827, 1828-32 are missing, there are no Willifords in 1833. Elizabeth Williford appears in place of John in the 1834 tax list, John Williford heirs appear 1835, Elizabeth appears 1836, but not thereafter). Nancy is probably the female in his household 10-15 in 1810 Knox and 18-26 in 1820 Harlan. (Simeon Wilson is alone at that census next door to John Williford and in close proximity to John Wilson). There are numerous Willifords in early Bertie County (now extinct), along the NC coast. They are major slave owners. Many migrated to extreme western KY and continued to hold large numbers of slaves. The connection of this John Williford to that family is unknown. Some elements of this family abided briefly in Spartansburg District of SC before going first to TN, then to KY. This is consistent with Nancy being born in SC. Nancy stated (‘testimony’ of grandson Felix Lewis) she lived among the Indians as a child and that is consistent with her being born in the Spartanburg District which was the Cherokee heartland. One John Williford was a participant in the pivotal RW Battle of Kings Mountain (10-7-1780). This may or may not be the same person (this John Williford would have been a teenager 15-19 when the battle took place). There is a James Williford (b 1770-1775) in 1820 Clay in close proximity to Dillon Asher (head of Redbird); he is also found in 1830 Clay. The fairly close proximity of John and James leads you to believe they were connected (based on age they could easily be brothers). In 1820 James also has a female 16-26 that could be Nancy. There is a Williford Branch in the Laurel Creek area of Clay, presumably named after Jim. Also, there is a Williford family in 1800 and 1810 Madison (Otter Creek north of Richmond). The last are well documented, but the connection to John is unknown. John Williford was married to Elizabeth (last name unknown) at his death, but it is conceivable that she is his second wife and is not Nancy's mother.