The marriage between Hugh McAlindon and Mary McConaghy was registered on 14.1.1890. It is on the GRONI site but the spelling makes it difficult to find (even when you use the variant option).
The two possible earlier marriages Roger has referred to were to Jane Gray on 30.6.1881 and Sarah Conway on 6.1.1882. If you pay to view all 3 marriage certs you should find out which of the earlier marriages was the correct one (by fathers names, occupation and perhaps townland).
We obviously don?t know exactly where Hugh was born save that it was Co Antrim. However if it was in Aghagallon parish then there?s a chance you may be able to trace his baptism. Aghagallon RC baptisms start in 1828. The records are on-line on the rootsireland site (subscription) and there?s copies in PRONI Belfast and the National Library in Dublin. Searching the index to Aghagallon records for the baptism of Hugh McAlinden 1842 ? 1852 on rootsireland got two matches. You?ll need top pay to view the full results.
Hugh McAlinden is listed in Griffiths Valuation for 1862 on plot 16 which he framed jointly with Edward McAlinden. That property today is on the Derrymore Rd on the loughshore, near Holy Trinity primary school.
http://www.askaboutireland.ie/griffith-valuation/index.xml?action=nameS…
Looking at the revaluation records for Derrymore, I can see that the townland is full of McConaghys and so that would suggest it was Mary Ann?s own townland.
http://www.proni.gov.uk/index/search_the_archives/val12b.htm
In 1900 Hugh split plot 16 into two, keeping 16a for himself (a house, and 5 acres). Plot 16b was James McAlinden with 1 acre, outbuildings and an extra shed added in 1900. Up to that time the properties had been rented but in 1906 they both purchased the freeholds under the Land Act (i.e. with a Government mortgage). James McAlinden also acquired plot 17 in 1903. He also had a house only on plot 24 which changed to Thomas McConaghy on an unknown date around 1900.
Hugh McAlinden moved to plot 18b (a house and garden in 1910), taking over from James McConaghy. James took over his farm on plot 16. Hugh was replaced by Mary in 1924 suggesting he had died around that time.
I noted the following probate abstracts on the PRONI wills site:
Probate of the Will of James McAlinden late of Derrymore, County Antrim, Farmer, who died 7 October 1921 granted at Belfast 2 November 1921 to James Edward McAlinden, Farmer. Effects ?198 18s. 11d.
McAlinden James Edward of Derrymore county Antrim farmer died 25 January 1953 Probate Belfast 11 November to Susan McAlinden spinster. Effects ?2552 5s. 5d
The wills themselves are not on-line but are held in paper format in PRONI.
There are numerous McConaghy wills listed there too, should you wish to look them.
http://www.proni.gov.uk/index/search_the_archives/will_calendars.htm
Tip: if searching the PRONI wills site, if you enter Derrymore in the box marked ?Full abstract? it will limit the results to that townland.
A little bit of the 1851 census for Aghagallon has survived. Unfortunately it does not include Derrymore. However if you visit PRONI, you can look up the tithe applotment records for the parish (c 1825) and there may be McAlinden and McConaghy households listed there.