Do you have some dates for Alexander & Elizabeth ?
It could help your search if you know any additional details, such as when and where they married, or where children were were born etc...
I dont see any sign of your Alexander on the 1901 or 1911 census for Ireland and no Chapman households at Swith's Row Dublin city, or any sign of a marriage that I can see in the civil records, or any sign of births of any children to the couple in Ireland. The more recent birth records, i.e. after 1919, are not available online.
I see a likely death for your Alexander in 1947, reported age 56 (born c1891), place of death and residence St. Eithne's Road, Finglas in North Dublin, occupation coach builder. The informant is his widow Elizabeth.
EDITED : I see a very likely match for Alexander & Elizabeth's Meagher marriage in Scotland - 1925 in Blythswood, the ref. on ScotlandsPeople is 644/10 1250. Blythswood district is part of Glasgow. Could this fit the timeframe you have for your Alexander & Elizabeth ?
Scottish Marriage certs are very detailed and include names of mother and father of the bride and groom. You need to purchase a few credits to access the full details.