I went to the LDS Library in Los Angeles today with good results!

I found the microfilm record for the Presbyterian marriage of James Smyth and Mary McKinley, dated 26 Apr 1849. The record says that he's from Corkhill & she's from Drummond. His father is James.

They have at least 3 children: Priscilla b1867, Robert b1870 & Anne b1866. They were christened in Clonavaddy. I can't find a birth record for Mary Smyth yet though...