Hi Rick If James and Sarah married in Scotland have you got their marriage record? Scottish records are quite good and should at least furnish you with both father and mothers’ names and occupations for the bride and groom. You can order the record online at http://www.scotlandspeople.gov.uk
If the couple were not well off, then it may be worth checking the Poor Law records to see if either of them or their children claimed for assistance. Glasgow Poor Law records can be very detailed and are often the key to pinpointing exactly where in Ireland someone was from. Unfortunately these are not online but need to be consulted in person at the Mitchell Library in Glasgow.