The Hannah Dewey that was baptized in Lebanon Township, New London, Connecticut on 14 May 1723 is not this Hannah. That Hannah was born to William Dewey and Mercy Saxton and on 22 Dec 1742 she married Silas Phelps and had several children with him.  Silas didn't die until 1816 so it is unlikely that his wife Hannah would have married Allen Breed.
Colonial Families of the United States: William Dewey
The Hannah Dewey that married Silas Phelps died on 24 Oct 1785 and her tombstone, shown on Find A Grave, clearly shows her as a wife to Silas Phelps. 
Research to determine this Hannah's vital records is warranted. Most genealogies ("The Breed Family Association" and "History of the town of Stonington", both used as sources on this profile) do not list any vital records for Hannah.
↑ Find A Grave, database and images (accessed 25 June 2019), memorial page for Hannah Dewey Phelps (14 May 1723–24 Oct 1785), Find A Grave Memorial no. 46157631, citing Old Cemetery, Lebanon, New London County, Connecticut, USA ; Maintained by John Beckstein (contributor 46939506) .
History of the town of Stonington, county of New London, Connecticut, from its first settlement in 1649 to 1900 by Wheeler, Richard Anson. Book published 1900 and digitized by Google from the library of the University of Virginia Publisher New London, Conn., Press of the Day .787 pp.; p. 245, no. 13: https://archive.org/stream/historyoftownofs00whee_1#page/n267/mode/1up
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It may be possible to confirm family relationships with Hannah by comparing test results with other carriers of her mitochondrial DNA.
However, there are no known mtDNA test-takers in her direct maternal line.
It is likely that these autosomal DNA test-takers will share DNA with Hannah: