Son Job married, and he and wife Rosanah (maiden name said to be Bell but without my viewing a record) had children, only one of whom, another Job J., survived to marry and have chidren.
Joshua Jr and wife Margaret had several children, and their family was enumerated on the 1860 census beside Joshua and Nancy. (See Joshua at left.)
Elizabeth apparently died before reaching adulthood.
Thomas married, but he and his wife Mary Ann were childless at the time of the 1870 census and the 1880 census when Mary Ann was age 40.[Federal Census, 1880, Cooke County, Texas, Precinct 7, page 22, stamped B or 373]
Daughter Nancy married and had children. ["Mississippi, Tippah County Marriages, 1858-1979," FamilySearch (https://familysearch.org: W C Mc Coy and N M Siddall, 26 Feb 1866; citing Marriage Registration, Tippah, Mississippi, United States, p. 80]
Widowed Nancy lived with son Thomas when enumerated in the 1870 census. [page 246A, Tippah Co, MS]
Buried in the cemetery with Joshua and Nancy are several other Siddles/Siddalls, and one of them, J. J. Siddall, 9 February 1823 to 1 February 1901, is probably their son Job while Roasanah Siddall, 30 March 1822 to 28 November 1881, appears to be Job's wife based on the 1850 and 1860 censuses. The others, none of whom survived to adulthood, are Job's and Rosanah's children. [findagrave.org: Tippah County, MS]
The 1850 federal census lists Joshua H. Siddle, age 58, Nancy, 44, Job J., 26, Joshua H., 24, Elizabeth, 11, Thomas J., 9, and Nancy, 7. [page 528A, Tippah Co., MS]
The 1860 federal census had Joshua Siddall, 68, Nancy, 52 or 54 (very unclear), Thomas J., 20, and Nancy, 17. Just below but in a separate household were Joshua Jr, 32, Margaret, 30, John, 10, Joshua, 6, and Nancy, 4. [page 488, Tippah Co., MS]
Note 1: A photo of the gravestone for Joshua in Walnut Creek Cemetery shows it to be badly weathered and partially illegible. The poster provides a birth date from the stone as 21 May 1792, and I could discern a date that appeared to be May --92. That date appears likely correct for a first child from the parents' marriage date.