Complex sentence: As was customary one of the children of the Castelli family was ordained into the priesthood, and Juan José was chosen for this, being sent to study at the Colegio Monserrat, part of the University of Córdoba.
Split into simpler sentences: As was customary, one of the children of the Castelli family was ordained into the priesthood, and Juan José was chosen for this. He was sent to study at the Colegio Monserrat, part of the University of Córdoba.