Hamilton County was formed in 1819. Bledsoe County (Pikeville) was formed in 1807. So, it is possible that flintlock rifles were made there. However, the style that people refer to as "Soddy-Daisy" (more properly "Soddy-Daisy-Pikeville") is a late target (over the log shooting) style. A more advanced collector can correct me if need be, but what I am saying is that a flint rifle from that area would be earlier than what we describe as Soddy-Daisy style. So, a flint Soddy-Daisy wouldn't look like a Soddy-Daisy.
Respectfully, it is your build, do what satisfies you, but first go through Jerry Nobles' "Notes on Southern Rifles" and you will know a lot more about southern rifles. I have been going through them, but one of my volumes is somewhere else; if I find a flintlock Soddy in it I will let you know. Volume One shows a great flintlock bear gun on page 148 that may be similar to what you are after, but it does not have the classic Soddy deep crescent buttplate, in fact it has no buttplate at all.
A Soddy-Daisy flint rifle irregardless of historical correctness would still be attractive looking, much like an East Tennessee bear rifle; not like those halfstock Hawken and Vincent rifles with a flintlock ignition.
This family history inspiration sounds like a fun project, I hope you update us as it moves forward.