I'll address the other parts of your message later, as time permits, but certainly I owe it to you right away to note my concern about the first link going back from Mary (Sale) Stewart/Stuart in the line you're trying to verify.
In my workbook, I show that Wm Sale (1720-1788) and his wife Ann did indeed have a daughter Mary, also known by the nickname Molly.I have posited a birth year for her around 1766 (as she was not above 45 years old on the 1810 census).However, this woman did not marry Henry Stewart / Stuart.Rather, she married (by bond dated 21 Jan 1782) Lt. Henry Martin in Wilkes County, NC.
I should mention in passing that the estimated birth year of 1725, which I used for many years, is likely wrong.Most importantly in that regard, when William was incarcerated on a British POW vessel in 1781, his age was given as 61.Assuming the accuracy of that record, William was born in 1720, or, if he was short of his 62nd birthday when the POW record was created, 1719.
The Mary Sale you identified may be in my notes somewhere, but right now I lack the time to hunt for her.
Note that at the time your ancestor Samuel Sale Stuart was born, the William Sale family was already in North Carolina, and had been there (either in Halifax or Wilkes) for at least 25 years.Accordingly, I suspect that Samuel's mother, Mary (Sale) Stuart, may have been from the Robert Sale or Anthony Sale branches.Assuming that Samuel's given name may have honored a maternal uncle or grandfather, it may be significant that Anthony Sale of Caroline County had a son Samuel (for whom William Hoard was appointed guardian in 1764).Whether this is the same Samuel Sale who was named a constable in Caroline County just six years later, I am not prepared to say just yet.
Now returning to the subject of Hannah (Jones) Sale Blackburn, her father was the William Jones of St. Ann's Parish, Essex County, whose will was written 19 Oct 1743 and proved 20 Mar of the following year -- 1744 on the Gregorian calendar, but still 1743 on the Julian calendar.
William Jones, in his will, named a wife Elizabeth, but I have no knowledge of her maiden name, and no proof that she was the mother of Wm Jones' three daughters.(We are all indebted to Antient Press, by the way, for making thorough transacriptions of the Essex County will books available in print.)I might assume that Elizabeth was the mother, but William's will doesn't make that clear.
I have never followed up on the clue provided in the will of Ann Sale in 1767 (pr. 1768) in which she left the rest of her lands "to be divided between Robert Sale's Children and Thomas Sale's Children."Conceivably if a person could find Henry Stuart in possession of part of that land, it would suggest that Mary was a daughter of Robert or Thomas; or possibly a granddaughter.
I hope this gives you something to work with, even if I haven't placed Mary (Sale) Stuart in just the right place.