Hi Janice.
I have just stumbled on your investigations with regard to Patrick Collins and Jane Mulligan which I find most interesting, as I have being doing similar work myself. Martin Collins and my grandfather Michael were brothers and grew up in Abbey, Loughrea, Co. Galway. Their father Patrick was born in Derrybrien and I'm informed that he worked for a local landlord (Lewis Estate) where he met Jane Mulligan who was also working there. Patrick had another brother Michael, who left Derrybrien and settled in the Mullagh area of Co. Galway (Drimatubber). He was married to a Mary OBrien. Alot of their family emigrated except for their daughter Kate who remained in the area. I, like yourself have been so far, unable to locate the marriage certificate of Patrick and Jane but I believe they were married in 1893 approx and settled in Ballygowan before eventually moving to Abbeyville nearby.
Jane from my findings was a trained nurse from Co. Meath and came to work on the Lewis Estate when she was still quite young. Jane born to Mulligan/Enniss is the only Jane Mulligan born in Co. Meath in this time frame so it looks very like this Jane was our great grand-mother.
Good luck with the investigations!
Helen.