There are a number of Churches / parishes in the vicinity of Castle Dillon which may hold records of your ancestors, the nearest would be Grange, Richhill, Kildarton, Kilmore & Loughgall.
St Aidans, Grange was the church of the Mollineaux family of Castle Dillon house so would be a possibility for a marriage if your ancestor actually lived at the house, as a servant or suchlike.
There is a gravestone at St Aidans, Grange as follows:
In affectionate remembrance of Mary McConnell late of Castledillon who departed this life 27th Feb 1871 aged 56 years.
My own family were from the area, many worked at Castle Dillon & I have searched all of the above church records both by visiting the churches and at PRONI who have microfilm for some of them. Some of the records may be online by now but I am not sure about that or which site/s.
More interestingly my 2 x great grandmother was Mary McConnell. She married John Creaney in the late 1830s but I have never been able to find the marriage. In my research I found a baptism in the books of Kilmore Parish Church for Mary McConnell in 1818, parents David McConnell & Mary, so Kilmore would be another possibility.
Very interesting link Kingskerswell, I was there a few months ago and took a number of similar photos of the old ruin. A real shame to see the place in this state, imagining the hustle & bustle of the place when my ggf was the butler and other relations were footman, coachman and a variety of servants.
Best of luck in your research Hampshire Lass.
tc