A lot of the rhetoric of southern-nostalgia songs seems to have been borrowed from Scottish Jacobite song (which was still an ongoing industry generating new songs at the time of the American civil war, and given a new lease of life, or at least twitching undead reanimation, by colour printing and the phonograph).

On the other hand, there isn't a tradition of Scottish sentimental song about loss comparable to C&W - Jacobite song didn't mutate in the way you're suggesting, it just fossilized.

Surely a lot of country was influenced by German and Russian Jewish sentimental parlour song and Thomas Moore Oirishry in the same way as Northern "Tin Pan Alley" stuff?