I would reckon you already have this information, but I thought I might post it just in case. However, I am afraid it does not answer the question at hand of who was Edmund Shackelford’s father.
"Phillip Shackelford, son of Captain Edmund Shackelford and his wife Judith Eastin, was probably born in Orange Co., Va. He moved to Elbert County, Ga., and was living in Madison County, Ga., 1807. The name of his wife is not known, but he had several children, including a son - Edmund Charles.
Edmund Charles Shackelford, son of Phillip, was born 1807, in Madison Co., Ga. He married Rebecca Elizabeth Hunter, in Greene Co., Ga., Oct, 5, 1836. They had several children, including sons Lloyd and William Alsa. Descendants still live in Georgia and Alabama."
Source: Shackelford Clan Magazine: Genealogy of Shackelfords and Shacklefords, Editor: T. K. Jones 716 Ave. A Lubbock, Texas