I have Flanagan Jemison's father as Henry Samuel Jemison (b. 19 Sept. 1844) and his mother as Frances L. Flanagan (b. 28 June 1854). If the Henry S. that you found in the census is this Henry Samuel, then he must have remarried and Artie and Robert T. must have been the children of this second wife Sarah. My records don't show a second marriage or those children. The children I have listed for Henry Samuel Jemison and his wife Frances Flanagan are William, Ella, Frank, Sam, Robert Beatrice, Flanagan and Bernice.
I have Flanagan's spouse as Nancy Ann Frances McIntyre. My notes say they had nine children. I have first names only for numbers 5-8: M.G., David, Thelma and Anette, though I have married names for them as follows: Mrs. I.W. Myrick of Bogalusa LA Mrs. W.E. Hudson of Pensacola FL Mrs. V.W. Walters of Evergreen AL Mrs. Frank Magraw of Saraland AL M.G. Jemison of Saraland AL David Jemison of Saraland AL Mrs. Thelma Hedrick of Indianapolis IN Mrs. G.T. (Anette) Evans of Saraland AL Mrs. J.D. Swaffer of Albuquerque NM
Henry Samuel Jemison's father was Robert Thomas Jemison (b. 23 Mar 1820 in Pulaski Co. GA) and his mother was Martha C. Pitts (b. 1826, d. 1852). Robert Thomas Jemison was the son of Samuel Jemison (b. 18 Aug 1783 in Lincoln Co. GA, d. 18 Sept. 1855 in Marion AL) and his second wife Nancy Coleman (b. 1787 in NC, d. Nov. 1861). Samuel Jemison was the son of Robert Jemison (b. 1723 in Ireland, d.17 Dec 1799 in Lincoln Co. GA) and Margaret Kirkham (b. 14 Feb 1755 in Augusta Co. VA, d. 2 Oct. 1831 at Tarversville, GA, daughter of Henry and Margaret Kirkham).