First of all Fitch interviewed two sons of Peter Parker, John C Parker and William H Parker. In both cases Fitch says he knew both of them well. As brothers they would have known their sister Esther very well. All of these Parkers lived in Whitehall in the late seventeen and early eighteen hundreds. So if the purported brothers were truthful not only do we know from their accounts that she was their sister but also that she was married to Nathaniel Hall. We also were able to prove that John C Parker was indeed the son of Peter Parker.

 In addition we took a photograph in 2005 of the tombstone of Esther Hall in Williams Cemetery, Whitehall NY. We could not find Nathaniel's tombstone but could see the name Esther Hall and the year 1808 on the tombstone. We also found an article in the New England Historical and Genealogical Register of someone who had written down the inscriptions of the tombstones in Williams Cemetery. From the looks of the arrangement of the inscriptions he listed them one after the other and sure enough next to the stone for Nathaniel Hall is one for Esther Hall that says that she died in 1808 at the age of 28 years and that she was Nathaniel's wife. The implied date of birth agrees with the date given in the article. 

Ester Parker Hall died 20 Mar 1808 at the age of 28. (3) Her youngest child at that time had been born about eleven months earlier on 14 Apr 1807.

Sources

(1) The Halls of New England by David Brainard Hall, 1883, page 258

(Family 152) Nathaniel Hall, pedigree as above. b. Sept. 19, 1776; d. Oct. 30, 1825; m. 1st March 4, 1801, Esther, dau. of Peter Parker, d. March 24, 1808, ae. 28 years; m. 2d, Dec. 8, 1808, Cynthia Maus, d. Jan 2, 1832; he resided at Whitehall, NY, was a lawyer and held the office of judge. In his personal appearance he was quite tall and broad shoulders, with prominent features, resembling in a remarkable degree the portraits of the celebrated Rev. Robert Hal. of England; they descended, probably, from the same ancestry in Warwickshire, England. Judge Hall was a man of very decided influence in his town and county. He died while on a visit to his kindred in his native town, Lebanon, N. H.

(2) Memorial of the Ancestors and Descendants of Peter Parker of Washing New York, by Asa Fitch., 1877

From 1847 to 1878, Dr. Asa Fitch of New York state collected a series of articles towards a history and genealogy of Washington County and the surrounding region. The numerous genealogical entries and family records featured in this manuscript trace the growth of the original families who arrived in the 1760s and the New England settlers who arrived just prior to the Revolutionary War, carrying their descent into the 3rd, 4th and sometimes 5th generations. At right are copies of his notes from his interview on August 16, 1850 with John Clark Parker, oldest son of Peter Parker.

pg 1 of interview with John C. Parker

pg 2 of interview with John C. Parker