Could I ask you a favour?
As I mentioned in my introductory email, in 1833 Donald is married to Ann McDuffie and has a son baptized at Kilmeny.
(I assume they were married because the child was not noted as illegitimate in the baptismal record.)
About 1836 Ann and her son leave for Canada with her parents and some siblings.
So what happened to Donald between 1833 and 1836?
He could have abandoned her, or he could have died of natural causes or in some accident.
Do you have in your records any information that might help, e.g. a newspaper clipping of a death?