At the age of 20, struck by the squalor of many churches with regard to vestments and altar vessels, she conceived the idea of an association of pious persons who would revive public adoration of the Real Presence of Jesus in the Most Holy Sacrament and contribute to providing altars and churches with worthy vestments and vessels. Thus was born (1848) under the direction of Fr. J. B. Boone the Association of Perpetual Adoration and the Work of Poor Churches, elevated to the rank of archconfraternity for Belgium in 1853 and for the whole world in 1873, and decorated with the title of Prima-primaria on 20 July 1895.
M. soon understood that to sustain and promote this work a special religious congregation was necessary, one that would take it seriously and serve as an incentive. She therefore founded (1857) the Religious of Perpetual Adoration, whose constitutions were approved by Pius IX in 1872. M. served as their superior general until her death. Besides their life of adoration, the sisters engage in catechesis, preparation for First Communion, and the making of sacred vestments.