Robed in the diplomatic immunity of a member of a reigning European royal family and possessed of great wealth, Marie was often able to help those threatened or despoiled by World War II. When the Greek royal family were in exile or Greece was under occupation, she helped support her husband's banished relatives, including allowing the family of her husband's nephew, Prince Philip of Greece, to occupy one of her homes in Saint-Cloud and paying for their private schooling while sending her own children to public "lycées".