Hi again Maggie,
I guess Christopher of Cleughbrae, Mouswald (son of a Smith or of a mother named SMITH?) might be an older brother of John and William of Roucan, Torthorwald (sons of a Smith).
But, as you say, they might be two quite different families.
And there are certainly pointers in favour of this conclusion.
I see that the Mouswald IGI batch is also (like the Torthorwald one) one of those infuriating batches where only the females have been extracted into the online IGI!
Added to which it is anything but clear whether "Smith" in the Mouswald entry is the occupation of the father John NICHOLSON (Smith) or (as transcribed) the surname (SMITH) of his spouse Mary Ann? It would be good to see some more of the OPR baptism entries.
Children (girls only online) of John NICHOLSON (Smith?) and Mary Ann (SMITH?) in Mouswald are:
Agnes NICKOLSON 1785
Janet NICKOLSON 1787
Mary Ann NICHOLSON 1791
which tends to lead one to the conclusion that this is a different family from the Roucan, Torthorwald one (John in Roucan, Torthorwald being 1787, and Janet in Cleughbrae, Mouswald also being 1787).
Some more OPR entries, and some Wills and MIs might help ...
JAP
PS: If you post on the Dumfries board, it would be a good idea to provide a link to this thread.