Her father, Johan Henry Weidner Sr., taught Latin and Greek at the Seventh-day Adventist Church in Collonges-sous-Salève, a village on the French side of the border.

A devoutly religious woman, Gabrielle was living and doing church work for the Seventh-day Adventists in Paris at the outbreak of World War II.

Following the 22 June 1940 signing of the agreement with the Nazis to create Vichy France, she returned to Paris while her brother went to Lyon where he established the "Dutch-Paris" underground.

With the help of her brother and other volunteers, she secretly coordinated plans for people to escape from occupied Paris, following the Dutch-Paris routes out of France into Switzerland or Spain.

In Fresnes she was treated fairly good, but when this trap did not work, she was shipped by railway cattle car to a concentration camp at Ravensbrück in Germany.