Hi Izzy
It is frustratring when the records start to dry up before 1855 and the start of official registration in Scotland. Only about a third of BMD events are to be found prior to 1855 in the Old Parish Registers, for all sorts of reasons.
Even if you were able to find a marriage entry for them, being pre 1855, likely it would be no more that a one-liner with no personal details relating to parents (at best, sometimes only a mention of bride's father's name, but most often not).
A good idea to look to possible death certs as if they died after 1855, normally full names of mother and father were included for the deceased if known to the informant.
Somebody has this online tree on a/try
http://trees.ancestry.co.uk/tree/34279853/person/19661807424, which includes the original image of John Kirkpatrick's death in 1892 in Kirkbean at the age of 88, already a widower of Elizabeth Begg. His father showing as a Dunholm Kirkpatrick, a carter. The informant did not know/remember the name of John's mother unfortunately. John and Elizabeth (Begg) had a son called Dunholm didn't they. It was Dunholm that reported his father's death.
Dunholm, son, also reported the death of his mother, Elizabeth Begg, in 1889. Showing as married to John Kirkpatrick. This connects with 1891 and son Dunholm with his family, and father living with them by then. The original census image from SP likely would show John as a widower.
The notes above are from the original images from SP that have kindly been included here on this family tree (available via a subscription).
Monica