Isaac van Dal was a son of Samuel van Dal and Vrouwtje van Staveren. He married Mietje Hamel in Amsterdam on 31 Juli 1912, a daughter of Levie Hamel and Marianna van der Velde.
City Archive of Amsterdam, archive card of Isaac van Dal and Mietje Hamel .
In addition, a Jokos file (number 51004) on this family is at the Amsterdam Municipal Archive. Access is subject to authorization from the Stichting Joods Maatschappelijk Werk.