Hi MLV,
I have had a look at my tree and I think Jim Harkess's father was Alexander Harkess, who was the youngest child of the James Harkess who drowned in 1892.
Alexander Harkess (b 1890 d 1960) married Rosina Lister ( b 1893 d 1961), could this be the grandparents of your mother in law?
Tom