Isaac Biedermann was a son of Maijer Markus Biedermann and Justine Kann. He married 30 October 1904 in Eindhoven to Regina Moses, a daughter of Jakob Moses and Maria Guggenheim. The couple had three children: one son survived the Holocaust; one daughter went to England in 1939 but their son Meijer Markus (unmarried) was killed in the Shoah.
Isaac self had another brother and three sisters: Karel, …