Mike:
Welcome to Ireland Reaching Out!
Unfortunately the RC church records for Athenry do not begin until August 1858 and civil registration did not start until 1864. I had searched on Roots Ireland for the marriage record or baptismal records for younger siblings but did not locate any records in Athenry. The first link below is the online parish register. I would go through the register looking for Healy records. The seond link is the 1856 Griffiths Valuation head of household listing which shows a Morgan and Patrick Healy in Castleturvin. The third and fourth links contain the 1901 and 1911 census records for a Patrick Healy familywith a son Morgan in Castleturvin. Patrick was shown as a farmer and manure manufacturer.
The fifith link below takes you to the online Irish phonebook. Search for Healy in County Galway (make sure you hit the Residential Tab). There are 4-5 Healy records include one in Castleturvin. Our privacy rules prevent me from providing you with the info directly.
Roger McDonnell
http://registers.nli.ie/parishes/0103
http://www.failteromhat.com/griffiths/galway/athenry.htm
http://www.census.nationalarchives.ie/pages/1901/Galway/Greethill/Castl…
http://www.census.nationalarchives.ie/pages/1911/Galway/Greethill/Castl…
http://www.eirphonebook.ie/