Together with Arondeus, she was part of the CKC resistance group that organised and executed the bombing of the population registry in Amsterdam on March 27, 1943, which destroyed thousands of files and hindered Nazi attempts to compare forged documents with documents in the registry.
Hun var sammen med bl.a. med kunsteren Willem Arondeus en del af CKC modstandsgruppen, som stod bag bombningen af folkeregistret i Amsterdam d. 27 marts, 1943, som destruerede tusindvis af dokumenter og forhindrede nazisterne i at sammenligne falske personlige dokumenter med rigtige.