Littleton Berry Abbett had at least one sister, eliza who married J.L. Callahan.(Joshua in 1860 & 1870 Census). Refer to Dist. 68, Pike Co., GA 1850 Census. Littleton Abbett and new wife Sarah Caroline are found in the Callahan home 13 Dec 1850.They had been counted already 7 Jul 1850 in their Tallapoosa Co. home.
The 1880 Census for Ward 3, Union Parish, LA shows a "Sister" Eliza Calahan in their household. No record has been found for children of Eliza and Joshua. I believe that Littleton named his only son, born 1872, Joshua, in honor of his brother-in-law, Joshua L. Callihan.
If you have more info about siblings please let me know.