Hello Janet, like yourself I could not find any records for the Stewart family but on the more hopeful front you give the mothers name as Caraher, this is an often misspelled name probably from Carragher.
The spelling you use is almost exclusively found in mid to north county Louth which borders on Northern Ireland and I see some BMDs in parishes adjoining Louth in Monaghan, and then in Northern Ireland in Armagh and possibly county Down. All references were for pre partition in Ireland which occurred in 1922.
There is a site here on Louth and you will find both names referenced etc but it is only for guidance as it does not have BMDs. http://jbhall.clahs.ie/
I live in Louth and am aware of the name as it occurs in a friends family here.
Good Luck
Pat