Joseph Fierlier was a son of Nathan Emanuel Fierlier and Roosje Swaab. He married 3 December 1913 in Amsterdam to Betje Vega, a daughter of Abraham Vega and Dientje van den Berg. The couple had three children: Roosje, Dientje and Nathan Joseph.
City Archive of Amsterdam, archive card of Joseph Fierlier and website www.wiewaswie.nl.