Vivian Hytovick, a South Branch Hoover-Penninger researcher, emailed me with a citation from Chalkley's Chronicles Vol. II regarding a debt Henry Stone of the South Fork had incurred in Tulpehocken ca 1755 (which was not pursued in court until 1791):ftp://ftp.rootsweb.com/pub/usgenweb/va/augusta/court/2court1...
Ctrl F for Stone on that page.
This likely proves that the literate immigrant, Henry Stone, was also in Tulpehocken after his arrival in 1751. He could, however, have not been the illiterate son of Sebastian Stone whose family arrived in 1748 nor could he have married Juliana Andre in 1750 (the year prior to his arrival).
I will update the chronology in the first post on this thread to reflect that Henry Stone of the South Fork incurred a debt circa 1755 in Tulpehocken.
Stein (Stone) is not an uncommon German name but the two Henrys also gave their sons the same Christian names so it would be worth family researchers checking to see if they were first cousins or maybe uncle and nephew.
Vivian - thank you for the update!