Mulvihull = Mulvihill?
Was there a "Greta" in that photo or is it "
Great uncle Michael" and "Great Aunt Josie"?
Are Jack and Kathleen children or adults in the photo?
At any rate the marriage certificate when it arrives will help.
It will give Mary's father's name and the witnesses - maybe Lillian is in the area.
Is "Balylongford" the place the family have as the birthplace of Mary, or perhaps just a place they lived in at a later time?
Do you know if/when/where/who Lillian married?
So far the closest family I have been able to locate on the censuses is this one:
http://www.census.nationalarchives.ie/pages/1911/Limerick/Broadford/Barnagarrane/637746/five children in the household: Bridget, Margaret, John (Michael John?), Lie ("Lil" on original), Josephine.
but six total children born to mother Mary - so perhaps Mary Jr was away from the household at the time?