Hi Trish
I see you are still working at the Wigtownshire McChlerys. Hi too to anyone else out there.
I'm not sure how up to date the Walton tree is on Ancestry, but I can add detail to the wife of Alexander McChlery, Isabella Taylor if you don't have it. Still unable to trace a birth or baptism for him, but his mother (Jean Caughie) died in 1855, so there is a full roll of spouse, children, etc. Name of parents is confirmed by his death certificate of 1894. The Milroy comes from James Milroy, who was married to Margaret McChlery, possibly Robert McChlery's sister.
Wigtownshire's Old Kirkyards MIs show James Milroy, Margaret Mcchlery, Robert Mcchlery, varoius other McChlerys and Isabella Taylor, his mother. Lots more information on the stone, but too tired to try to disentangle the different generations.

Jean