Catherine Sheahan married Thomas Stack, son of Thomas Stack, Banna Mountain, on 21 May 1871. Kate (Catherine) was the daughter of Johnanna Griffin and Thomas Sheahan of Liscahane, Ardert. I found this when I checked the Census Search forms at censussearchforms.nationalarchives.ie
We all know how difficult it can be to find the Mother's maiden name and how important it is when the father's name is relatively common. The Census Search Forms sought to establish a persons residence in 1851 and is one source we can use in the absence of the 1851 Census itself.
In 1853 ,Thomas Sheehan of Liscahane, Ardfert, was indeed renting land (upon which he had a house and outbuildings) from Sir Edward Denny with a Rateable Valuation of £25. 5 shillings according to Griffith's Valuation.
In 1901, there was 127 people living in Liscahane of whom 10 were Sheahans, Thomas age 55 and his wife Mary Stack originally of Banna and their children. They married 5 Feb 1870 in Ardfert. Their fathers were Thomas Sheahan and Thomas Stack. Is it possible that a Stack brother and sister married a Sheahan brother and sister?
It is interesting to note that on Census day they had a visitor called Lizzie Stack age 18 and that Kate & Tom Stack had a daughter Elizabeth aged 18.
Marriage of Kate Sheahan & Tom Stack 1871
Thomas b 1874
Mary b 1879
Elizabeth b 1882
Honora b 1884
John b 1891
Patrick Joseph b 1895
Banna Mountain 1901
Banna Mountain 1911
Death of Thomas Stack (born c1841) 1928, Bridget Stack of Kilorane present at death
Patrick Stack, son of Thomas Stack of Banna married Bridget Rahilly of Kilorane, 1921