The property that Alexander Morgan had in 1864 was plot 33, in Griffiths Valuation, which was a farmhouse, outbuildings and 12 acres of land. (IT would be easy enough to locate today, should you wish to do so. Plot 33 is on the modern Rowan Road, a mile or two west of Keady. Just on the border with Co Monaghan.) Immediately beside him were 6 other Morgan households which are likely to be relatives of his. The revaluation records show the property changing to Francis Morgan junior in 1874 which normally indicates Alexander had died by that year. Francis acquired the adjacent plot 33 in 1887 increasing his property to just over 15 acres. The property changed to Bridget Morgan in 1901 and then again to Thomas in 1907. Thomas purchased the property in 1914 under the Land Act (prior to that it had been rented) and he remained the occupant when that set of records end in 1929.
http://www.proni.gov.uk/index/search_the_archives/val12b.htm
By the 1901 census there were 4 Morgan farms there (one of which is the farm occupied originally by Alexander and by 1901 by Bridget and Thomas):
http://www.census.nationalarchives.ie/pages/1901/Armagh/Derrynoose/Rowan/
and in 1911
http://www.census.nationalarchives.ie/pages/1911/Armagh/Derrynoose/Rowan/
A couple of wills:
Full Abstract :
Morgan Felix of Rowan county Armagh farmer died 2 December 1927 Administration Belfast 29 March to Anne Murray married woman. Effects ?13 10s.
No Image
Full Abstract :
Morgan Joseph of Rowan county Armagh farmer died 29 March 1924 Administration Belfast 8 September to Catherine Morgan spinster. Effects ?23 1s. 1d.
Both died intestate. Copies of their probate files are held in PRONI, Belfast.
I can see a possible death registered in Armagh for Alexander Morgan in 1870. Est year of birth 1795.
Derrynoose RC parish records start in 1814. There are gaps. They are on the rootsireland site (pay to view). http://armagh.rootsireland.ie/ There appear to be 2 children listed for Alexander & Nancy: Pat in 1827 and Bridget bapt 1833. (There are likely to have been others but the records may be incomplete or illegible).