James Blanding (1781-1870), the son of William Blanding V and Lydia Ormsbee, had at least one brother, William Blanding VI, who was a physician in Rehoboth, Massachusetts. On April 24, 1811, James Blanding married Elizabeth Carpenter (1784-1865), the daughter of Revolutionary War veteran Caleb Carpenter, also of Rehoboth, Massachusetts. They had eight children: Susannah Carpenter, Elizabeth Parthenia, Nancy Augusta (1816-1887), Juliet (Juliette) Marie, William Willett, Abraham Ormsbee, Lephe H., and Sarah Murray. Nancy Augusta Blanding married John G. Nattinger, a merchant from Ottawa, Illinois, on September 25, 1856. Susannah Carpenter, Elizabeth Carpenter Blanding's sister, married Elizabeth's brother-in-law, William Blanding VI.
Noah Blanding (1795-1851), James Blanding's third cousin, married Rosanna Carpenter (1799-1859) on November 15, 1819. They had six children: Abby R. (b. March 5, 1822), Horatio N. (b. November 21, 1824), Esther B. (b. July 26, 1826), Noah H. (b. October 23, 1828), Elizabeth Carpenter (July 18, 1832), and Frances R. (January 31, 1839).