Have you read all the birth certificates for Jean & Matthew's children? The is lots of data on 1855, especially, and more than in USA for any year in 19th century. Did they die in Scotland? If they did, the death certificates will be very helpful. Good luck. Oh, by the way, my grandfather's sister, Elizabeth Frail, married Archie Kerr in Kilwinning in the 1870's. I don't have the date at my fingertips. There were lots of Kerrs, but could be related.