I am sorry but my information shows no Joseph Allen at the birthdate of 1642 in Sandwich or a son Benjamin b. 1703.The Joseph Allens that I have are one born 1633 or 34 probably Braintree (son of Samuel) and another Joseph b. June 24, 1654 Medfield. Married Hannah Sabin. His Father is James Allen who married Ann Guild. This Joseph did have a son Benjamin born Abt. 1656 in Medfield.Sorry I can't be of any further help.