Walsh Buckley marriage

Can anyone help with this query.  My great grandparents came from Mourneabbey - John Buckley of Monaparson, b1839 (son of Bartholomew Buckley and Margaret Duggan) and Mary Walsh c1838 of Mourneabbey. I cannot pinpoint a birth for Mary (born around 1838/9) as there are several "candidates".

I obtained baptisms for their children (including my grandmother Margaret Buckley b1870 Lahakinneen); from pp Donal McCarthy many years ago, but have since been trying to find a marriage for John and Mary.  On Irish Family History Foundation there are three marriages for people of these names marrying, two of which are far too early, however one is dated 21 January 1851 - in Grenagh.  This also would be too early as the couple would have been too young.  However, I wonder if the date has been transcribed wrongly - and 1851 - should be 1857?  Their first child Bartholomew was born 13 May 1858 in Mourneabbey, so 1857 would be a "good" date. I always cross a 7 with a small horizontal line to make sure it is not confused with a "1", so therefore wonder if someone has copied a 7 to a 1?

There is a birth for a Mary Walsh born 1839 Mourneabbey - parents James Walsh and Margaret Cooney - later this couple appear in Grenagh on births for their subsequent children and on Griffiths. A James Walsh was a witness at the above marriage.

I know births and marriages were not listed for Grenagh until later, so everyone was included in the Mourneabbey area.

Hope someone can shed some light on this one - very many thanks - Pat