Elizabeth "Betsey" Davis Brown was born about 1791. She passed away in 1848. She married abt. 1816 to Samuel B. Hallock.
Note that Davis is her middle name, not her surname.
Betsey Davis Brown was actually the step-sister of her husband Samuel B. Hallock, because she was the daughter of his father Jonathan Hallock's second wife Miriam Davis; Miriam Davis was previously married to Joseph Brown.
From the National Parks link below: "Samuel B. Hallock (1792-1836), fourth in descent, and fourth to occupy the house, did not outlive his father, Jonathan. He too is buried in the Hallock Cemetery. Having married his step-sister Elizabeth (“Betsey”) Davis (daughter of his father’s second wife, Miriam Davis) c. 1815, the couple had three children: Sylvester (b. 1816), “Captain” Heathcote (b. 1817) and Adelia (b. 1819). Samuel died at the age of forty-four on July 20, 1836. Heathcote also died young at the age of twenty-five on May 7, 1842. Following in his father’s footsteps, Samuel B. continued to farm the ancestral land and likely participated in diversifying his crops to include wheat, rye, buckwheat, hay, Indian corn, peas, beans and even potatoes, which were lately introduced. Livestock included cows, sheep and swine."
National Register of Historic Places: Noah Hallock House, Suffolk County, New York, section 8 page 7 
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