Izaak Ereira was a son of Caleb Ereira and his 2nd wife Klara Werkendam. He married Anna Beesemer in Amsterdam on 10 January 1917, a daughter of Levie Beesemer and Klaartje Godschalk.
The couple had three children: Clara, Celine and Rachel.
City Archive of Amsterdam, archive card of Izaak Ereira and website www.wiewaswie.nl.