I have to correct my post as I got my Peter Shoulders mixed up.
There is a Peter Shoulder (died between 1901 and 1911) whose father was James Shoulder who married Rose McElroy (died 1914) on 9 Oct 1874 in the RC Church in Crossmaglen, Union of Castleblaney, Co. Armagh and this family lived in Mounthill, Creggan, Armagh which had been the home of Rose McElroy whose father was Charles McElroy.
This Peter and Rose had at least two children, Mary (born and baptised 1875) and Bernard (1878). I think this Mary married a Patrick Agnew (father Thomas Agnew) and had a son John Agnew in 1907 but she died in 1908.
The Peter Shoulder in my family was baptised in Dundalk to my great-great-grandparents Arthur Shoulder and Mary Hanlon in 1841, and he was a brother of my great-grandmother, Margaret Craven ne Shoulder (b 1853). They had two other brothers, the oldest James (b 1838), then Patrick (b 1844) and a sister Mary (b 1846). Their parents Arthur Shoulder and Mary Hanlon married in Dundalk in 1838 and lived in the Kilcurry area moving around between Rathduff to Shortstone to Waterlodge and Balriggan, just north west of Dundalk. I think the eldest son James above (b Dec 1838) may have emigrated to Boston, Mass., USA as there is a James Shoulder listed there on the 1880 US Federal Census, who was from Ireland and aged about 40, not far off the correct age.
Shoulder is a very unusual surname and there are no Shoulders in the phone book in Dundalk now and there aren't even any in the Dublin one.
The same first names in the Shoulder family keep repeating, James, Patrick, Peter so I still think these families are all related to each other. It was such a small family in the Louth Armagh area. There were only 11 people with the surname Shoulder on the 1901 census for the whole of Ireland, and I am guessing most of them had emigrated by then.
I hope this might be of help to anyone researching the Shoulder family in Armagh and Louth.