Hendrika Wolffers was a daughter of Lion Wolffers and Ester Emrik. She married Simon Knap in Rotterdam on 13 March 1901, a son of Marcus Knap and Debora van Emrik. Hendrika and Simon had three children together, namely Debora, Esther and Willem. Her daughter Debora had an illegitimate child in 1926, named Simon, who lived in with his grandparents Hendrika and Simon. He was killed in Auschwitz on 30 September 1942. Her daughter Esther survived the war; she married a non-Jewish man but her son Willem has been killed on 30 September 1942 in Auschwitz too. Still in the summer of 1942 however he was married to Grietje Frenk, a daughter of Aron Frenk and Elisabeth Velleman.
Hendrika was deported to Auschwitz on 12 October 1942 together with her husband and upon arrival there both on 15 October 1942 immediately killed.
City Archive of Rotterdam, family registration card of Simon Knap; website www.wiewaswie.nl; the file cabinet of the Jewish Council of Amsterdam, records of Simon Knap, Hendrika Wolffers, Simon Knap (1926), Willem Knap, Grietje Frenk and an addition of a visitor of the website.