It looks like Nancy & Clarissa Selden did marry the Thayers of Palmyra, NY.
A genealogy of the descendants of John May who came from England to Roxbury in America, 1640 Boston: Franklin Press; 1878 page 89 The children of Edward and Sibyl (May) Selden are named in this book: Mary b. 1780 Sibylborn 1782, m. Dr. Hart of Durham, NY. Nancy born 1784, m. Thayer, Palmyra, NY Clarissa born 1786, m. Thayer, Palmyra, NY Delia born 1788, m. Strong of Hudson, CT Edward, born 1790, merchant, Pittsburg, PA Charlotte born 1792, m. Rev Sylvester Eaton
My note: It looks like the newspaper named the wrong Selden daughter who married the Rev Eaton.