The Institute, which includes 14 of the 17 Mercy congregations, is to take effect on 12 December, the anniversary of the founding of the Sisters of Mercy by Venerable Catherine McAuley in Ireland.
Since 2005, the 17 Australian congregations and the Autonomous Region of PNG, which has been federated within the present Institute of Sisters of Mercy of Australia since 1981, have been searching for the best way to nurture their unity and to strengthen their capacity.
Sister Nerida Tinkler, President of the Institute said: "This search has involved much prayer, frequent theological reflection on the social needs of our time, careful study of the life and ministry of our founder, Catherine McAuley and her vision for religious life, and several comprehensive consultations in which all sisters were encouraged to participate.
"Eventually it led us to the point where 14 of the congregations, as well as the Autonomous Region of PNG, decided to petition the Holy See for permission to relinquish their independence and to come together as one new congregation."
In July, the Holy See approved the proposal and on 12 December each of the 15 groups will cease to be a separate canonical and legal entity and its sisters will become members of the new Institute.
The 15 uniting groups, comprising some 930 sisters, are: Adelaide, Ballarat East, Bathurst, Cairns, Goulburn, Grafton, Gunnedah, Melbourne, Papua New Guinea, Perth, Rockhampton, Singleton, Townsville, West Perth and Wilcannia-Forbes.
The foundation of the new Institute will be celebrated with a Eucharist in St Mary's Cathedral, Sydney, on 18 December at 2pm.
Source: Catholic News, 21 November