Newbury Isaacs: Richard b.1621 m. Abigail_____ Samuel b.1645 m. Eliz. Titcomb Richard b. 1679 m.1 Abigail Ropes m.2 Sarah Bayley Benjamin b. 1708 m. Jemima Parkhus-their sons were, Enos b.1741 and Isaac b. 1749
Isaac b. 1749 m. Rebecca Sargent did not have a son named Isaac
Enos b 1741 m. Sarah____ and had son Isaac b.March 25,1774I do not have the info on this Isaac's marriage etc. but looks promising for you!