I have an Aunt Barbara (nee Duggan) in Memphis but her surname does not start with an 'S' so it must not be the same person. She would be a good one to talk to, as she has a lot of the family history.
Let me know if you have any holes to fill and I will help as best I can. I had no idea BF Duggan was a Confederate Capt, though it should not surprise me. I have several of his books and even one piece of his furniture, actually. One of the more notable titles is, "A Biblical Defense of Slavery." The message of that book is "other-worldly" and disturbing to my modern ears but from an historical perspective it is very interesting.