May I make a little suggestion? Sloan and Jackson are fairly common names, so dates of some kind would help. Do you know when and where John & Cynthia were born, lived, or died?
I found what looks like some of their children on the TX Dth Idx thru 1976:
Name: Decia Kelly Death Date: 04 Apr 1933 Death Place: Paint, Rains, Texas Gender: Female Race: White Death Age: 57 years 5 months 1 day Estimated Birth Date: Birth Date: 03 Nov 1875 Birthplace: Grayson, Texas Marital Status: Married Spouse's Name: Father's Name: J. W. Sloan Father's Birthplace: Miss. Mother's Name: Synthia Jackson Mother's Birthplace: Ala. Occupation: Place of Residence: Cemetery: Pilot Grove Burial Place: Burial Date: 05 Apr 1933 Additional Relatives: Film Number: 2115359 Digital Film Number: 4163856 Image Number: 3286 Reference Number: 19840
Name: Paralee Winstead Death Date: 25 Jun 1961 Death Place: Gainesville, Cooke, Texas Gender: Female Race: White Death Age: 77 years Estimated Birth Date: Birth Date: 20 Aug 1884 Birthplace: Texas Marital Status: Married Spouse's Name: Father's Name: John M. Sloan Father's Birthplace: Mother's Name: Cynthia Jackson Mother's Birthplace: Occupation: Housewife Place of Residence: Munster, Cooke, Texas Cemetery: Rest Haven Memorial Park Burial Place: Gainesville, Texas Burial Date: 26 Jun 1961 Additional Relatives: Film Number: 2116748 Digital Film Number: 4166594 Image Number: 1063 Reference Number: 38325
Name: John Gipson Sloan Death Date: 05 Jan 1950 Death Place: Whitewright, Grayson, Texas Gender: Male Race: white Death Age: 82 years 6 months 27 days Estimated Birth Date: Birth Date: 08 Jun 1867 Birthplace: Texas Marital Status: Married Spouse's Name: Father's Name: J. N. Sloan Father's Birthplace: Ken. Mother's Name: Cynthia Jackson Mother's Birthplace: Texas Occupation: Farmer Place of Residence: Pilot Grove, Grayson, Texas Cemetery: Pilot Grove Burial Place: Pilot Grove, Texas Burial Date: 06 Jan 1950 Additional Relatives: X Film Number: 2074223 Digital Film Number: 4030079 Image Number: 2182 Reference Number: cn 1975
Decia's DC says she was born in Grayson Co, TX, so I checked a book I have in my possesion (my husband and his mother both born there) "An Illustrated History of Grayson Co, TX", by Landrum and Smith:
SLOAN, John M. m 22 Apr 1858 Cynthia C., dau William Jackson
JACKSON, William b Tenn c 1810 -- m Sarah b Ala c 1815 -- Ch: Martha A. b Ark c 1835 (m 8 Mar 1851 Jams Longley, Josiah b Ark 1837, James P. b Ark c 1839, William A. b c 1841, Cynthia C. b Ark c 1844 (m 1858 John M. Sloan), Robert A. b Ark c 1846, Mary Elizabeth b Tex c 1848, Samuel b Tex 1850, Liea b Tex c 1852, America b Tex c 1856, George A., b Tex c 1859. Sources according to the book are from the 1850 and 1860 census.
Go to Rootsweb's WorldConnect site -- http://wc.rootsweb.ancestry.com/cgi-bin/igm.cgihttp://wc.rootsweb.ancestry.com/cgi-bin/igm.cgi -- enter Jackson, Cynthia, father William, mother Sara, spouse Sloan. Several matches, but I clicked on the one with the most little icons. Looks like John Rose can take Cynthia's line on back a ways. Contact him, find our his sources and share what you know about your family.