Regarding your grandfather's name of Robert Huckabee Addington: My ancestor James Addington, b. April 1827 (son of James Addington and his wife, Winnifred Woodfin) had a brother named Joseph Huckabee Addington. Perhaps your grandfather'smmiddle name is a connection to this Joseph.
The little information that I have on him is that Joseph was born 14 Dec 1824 NC; d.21 Aug. 1862 in Waleska, Cherokee co., GA.
He married his distant cousin, Martha Susanna Addington. Born 14 June 1830, SC, to John T. Addingotn and Rachel Miller; m. 23 Sept 1849 in Gilmer co.,GA; d.Jan 1913 Waleska, Cherokee co.,GA. Martha'father John wsthe son of James Addington and Rebekah Garrett. Both Martha and husband James are reported to be buried in Briar Patch Cem., Waleska, Cherokee co.,GA.
I have not deeply researched this familygroup, so I do not know whether or not this information is absolute fact. I hope it helps, though.