I don't get on this site very much. I did find Thomas and Louisa in McNab twp, Renfrew co in the 1881 census. They list their religion as presbyterian while in the 1891 census it's listed as R.C. So I think they were married in the presbyterian church. You might want to contact the Carleton Place public library to see if they have the newspaper microfilm to check for an obit for Louisa. if her siblings are mentionned, the parents maybe found through them.