Facing the German invasion in 10 May 1940 during World War II, the Grand Ducal Family of Luxembourg left the country to find refuge in Portugal, after receiving transit visas from the Portuguese consul Aristides de Sousa Mendes, in June 1940.
After travelling through Coimbra and Lisbon, the family first stayed in Cascais, in Casa de Santa Maria, owned by Manuel Espírito Santo, who was then the honorary consul for Luxembourg in Portugal.
During their stay in the country, Marie-Gabrielle and her sisters attended the "Collège Jesus-Marie de Sillery",[5] in Québec, and settled in the "Villa Saint-Joseph", inhabited by their paternal aunt, Princess Zita of Bourbon-Parma, Empress of Austria, which hosted them.
[6] Later, Princess Marie-Gabrielle studied sculpture with Auguste Tremont:[7] in 1950, she exhibited her works at the Salon des Animaliers in Paris, under the pseudonym, "Mademoiselle de Clervaux".
[9] Princess Marie-Gabrielle met her future husband Count Knud Johan Ludvig of Holstein-Ledreborg (2 October 1919 – 25 June 2001), descendant of Count Ludvig Holstein-Ledreborg, at the 1946 silver wedding of her uncle Prince René of Bourbon-Parma and his wife Princess Margrethe of Denmark, which was celebrated at 'Bernstorffshøj' - the home of Prince Axel of Denmark.