Bishop McGuckian, who has been Bishop of Down and Connor since last April, will be accompanied by Bishop Brendan Leahy of Limerick.
Sr Mary, OLA, is the daughter of parents from Ballintra who was educated in Drumoghill NS and Loreto Secondary School in Letterkenny, and is President of the International Union of Superiors General.
This Synod on Synodality will be attended by Church representatives from around the world and will sit from 2 – 27 October on the theme: ‘For a Synodal Church: Communion, Participation, and Mission’.
Bishops McGuckian and Leahy also attended last year’s assembly.
"The methodology was hugely significant,” Bishop McGuckian said.
“We gathered in Rome for four weeks, we used Conversations in the Spirit - a particular way of being around a table, where everyone speaks in their turn and everyone listens respectfully.
“There was a genuine listening for what the Spirit was saying in my heart, as I listened to others. Then there was an effort to find where the convergences were, as well as the divergences.
“To do that all day every day for three or four weeks was quite transformative for me personally . . . That is a huge take away, that I have brought home and used and have found extremely enriching. I now feel going back this year that I have that experience behind me, and that this year I bring a capacity, or aptitude for Conversations in the Spirit."
A penitential service will be held in St. Peter’s Basilica on the evening of October 1 and the second session gets underway on October 2 after the opening Mass.
The task of the second session is to complete the discernment begun at the first session and offer the result to Pope Francis in a final document.
The work of the synodal assembly – through plenary sessions known as “general congregations” and working groups – will be divided into five “modules” which mirror the sections of the Instrumentum laboris: Foundations, Relations, Pathways, Places and Conclusion.
The concluding module will be devoted to the discussion and approval of the final document which will go to Pope Francis, who is responsible under the Apostolic Constitution Episcopalis communio for its implementation.