Hi there,
Do you know if any of the couples that you listed have any children? This might help you try and work out the potential parents of the couples by way of the Scots naming pattern. Also, have you found them on any census records? 1841 onwards is available on Scotlands People, and there is some coverage on Freecen.
Also, did any of them libe until 1855 or beyond? If you can find death certificates for any of them, that may also help.
Cheers,
Clare