When we were children, members of the “Children of Mary” wore a habit to Mass, but not at home. I remember us boys had a blue cassock and a blue belt with a rosary attached. But, to differentiate from clergy, we had a detachable collar which overplayed the top of the cassock in the same way the choristers of Westminster Cathedral dress, without the tie. The girls wore blue dresses and blouses, white shirts and also fastened a rosary to their belt.
OH and we wore a big Miraculous Medal with a blue ribbon around our necks. But not just every Mass, only for special ones. Feast days and such.