After many years service with the French speaking Walloon JOC in Belgium prior to World War II, Marguerite took up the reins of animating the newly launched IYCW International Secretariat following the end of the war in 1945.
Over the next 12 years, Marguerite carried out a heroic labour in animating the emerging IYCW network around the world. She retired from her position in 1957 following the First International Council of the IYCW in 1957.
For the next 10 years, she worked with Cardijn as his personal assistant and secretary.
It was Marguerite who in fact compiled Cardijn's only book, Laymen into Action, a collection of Cardijn's speeches and writings, that were compiled as a contribution to Vatican II.
Following Cardijn's death in 1967, Marguerite with Jacques Meert and Professor Aubert wrote the biography of Cardijn, The Life and Times of Joseph Cardijn.
She also wrote a biography of YCW co-founder, Fernand Tonnet, following his death in a Nazi concentration camp in 1945.
After finishing with the IYCW, Marguerite took on the herculean task of cataloguing Cardijn's personal archives now housed in the Royal Archives of Belgium.
Towards the end of her life, she took on the task of cataloguing the archives of the IYCW.