Great stuff, Pat.
An original T206 collection from South Carolina, which I acquired back in 2006 of approx. 400 cards essentially reinforces your research.
This collection of assorted PIEDMONT 150 and 350 cards included 29 - OLD Mill Southern Leaguer's. The owner of these cards got them
from his Grandfather, who he said collected them in his youth exclusively in 1909.
TED Z
T206 Reference
.