Hi again bridgewaterwolfie,
I think you have a very difficult task here unless you limit yourself to working with confirmed data records. Your name is Cloy and you say you have some link to the couple Robert Cloy and Elizabeth Mcguffog. However there are no records for this couple, but there are records for the couple Robert McCloy and Elizabeth Mcguffog. So are you originally a McCloy?
You mention Elizabeth McGuffie in relation to a death record & there is an Elizabeth Mcguffie (1763-1837) on the Find-a-grave website, but she was married to a Peter McKie (not Robert).
Sometimes the Census returns can help sort out problems of this nature, I've had a brief look on the Freecen website but there is no obvious solution. Maybe an in depth check of the census records will help:
If you go on Freecen website (
https://www.freecen.org.uk/) it has good coverage for most of the Scottish census years in Wigtownshire, best of all its totally free.
Good luck and best regards