Sarah-Louise,
I looked for the Porter-Cochran marriage but could not find it either.
To answer the question about whether PRONI would have a copy of the Blakely - M'Kee marriage certificate, the answer is that it depends. Sometimes they do have them and sometimes they don?t.
The main repository for statutory births, deaths & marriages in Northern Ireland is GRONI, in Belfast (the Northern Ireland equivalent of GRO). However GRONI don?t offer a photocopy option and they charge ?15 for a full certificate. So GRO is much better value (at ?4 for a photocopy) and I would generally point people in that direction, unless it was for a certificate in Northern Ireland after 1.1.1922 in which case you have to use GRONI.
PRONI holds copies of baptism and marriage records (all denominations). Their focus is on those before statutory registration, and so a lot of their records stop around 1864 (1845 for non RC marriages) because the information after those dates ought to be in the statutory records. However with some churches, especially smaller one with fewer records, the copying team obviously bashed on regardless and in some cases there are marriages certificates right through until the 1960s. (And they are all free to view. 30p to copy).
So you have to know the church where the marriage took place, and then check the PRONI site to see how far the records go, and therefore whether you can get a copy there. Otherwise stick to GRO, is my advice. In this case we don?t know which church the marriage took place, and so you wouldn?t know where to look in PRONI. So get a copy from GRO.
When you get the certificate, let us know the townlands (addresses), occupations of the couple, also their fathers names and occupations, and we'll see if we can find them for you, in Griffiths valuation, and perhaps the 1901 census, if they were still alive.
Elwyn