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The records for Burriscarra/Ballintober RC parish start in 1839. So if Michael and Eleanor were from that parish, baptismal records would not be available.
I searched the subscription site Roots Ireland and located a baptismal record for a daughter Mary born in 1840. See below. Did Michael and Eleanor emigrate after 1840?
Name:Mary SaundersDate of Birth:
Date of Baptism:10-Nov-1840Address:KilavolanParish/District:Burriscarra RC parishGender:FemaleCountyCo. Mayo
Father:Michael SaundersMother:Eleanor SheaOccupation:
Sponsor 1 /
Informant 1:Bryan SheaSponsor 2 /
Informant 2:Mary Sanders