Sr Mary Augustine and her companion, Sr Mary Catherine, returned to Dublin in August 1815, and Dr Murray appointed Sr Mary Augustine as the Superior of the new Community. The Sisters made the usual three vows of religion – chastity, poverty and obedience – and an additional fourth vow to devote their lives to the service of the poor. The following year, Dr Troy canonically established the new Institute under the title of ‘Pious Congregation of Sisters of Charity’.
Soon after its establishment, the Sisters began their visitation of the poor, and found that the Rules of the Constitution of the Society of Jesus which they had chosen to follow were not suited to the type of apostolic life of their new Institute. A new Constitution was drafted by Sr Mary Augustine, with the assistance of a Jesuit Priest, and was submitted to Rome for approval in 1824. The Rules and Constitution were deliberated on in Rome during the pontificates of Leo XII and Pius VIII, but it was not until after the accession of Pope Gregory XVI that they were finally approved in 1833.