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Here is the 1873 civil marriage record for Thomas and Mary which lists the names of the fathers of the bride and groom. Mary was from Trellick townland https://civilrecords.irishgenealogy.ie/churchrecords/images/marriage_returns/marriages_1873/11265/8208317.pdf
I looked on the subscription site Roots Ireland for baptismal records for Thomas and Mary. There were Thomas Corless baptimsal records in the 1840s but none in Kinvarra, I did find a Kinvarra record for Mary in 1846. See below. They were living in Carrownamaddra townland in Kinvarradoorus civil parish.
Name:Mary StauntonDate of Birth:
Date of Baptism:06-Feb-1846Address:CarunnamadraParish/District:KINVARAGender:FemaleCountyCo. Galway
Father:John StauntonMother:Elizabeth HealyOccupation:
Sponsor 1 /
Informant 1:Patrick CallinanSponsor 2 /
Informant 2:Honor Healy