Hi Julie
Unfortunately the early Irish Censuses don't have both Tipp & Kilk info so no luck there.
However the Tithe Applotments (free at http://titheapplotmentbooks.nationalarchives.ie/) have 17 Gradys in Roscrea in 1823 but only 1 in Thomastown in 1833.
The earliest birth/baptisms on www.rootsireland.ie/ are from Kilkenny:
Name:Michael GradyDate of Birth:
Date of Baptism:09-Oct-1768Address:Not RecordedParish/District:ST. MARY'SGender:MaleCountyCo. Kilkenny
Denomination:Roman Catholic
Father:John GradyMother:Not Recorded GradyOccupation:
Sponsor 1 /
Informant 1:John BonhamSponsor 2 /
Informant 2:Mary Kavanagh
Name:Patrick GradyDate of Birth:
Date of Baptism:19-Apr-1772Address:Not RecordedParish/District:ST. MARY'SGender:MaleCountyCo. Kilkenny
Denomination:Roman Catholic
Father:John GradyMother:Mary CarrollOccupation:
Sponsor 1 /
Informant 1:Laurence WilliamsSponsor 2 /
Informant 2:Eleanor Turneer
You didn't give a birth year for Martin but here's a possible:
Name:Martin GradyDate of Birth:
Date of Baptism:02-Jan-1826Address:Not RecordedParish/District:ROSCREAGender:MaleCountyCo. Tipperary
Denomination:Roman Catholic
Father:Patrick GradyMother:Ellen PineOccupation:
Sponsor 1 /
Informant 1:Mary ClarkeSponsor 2 /
Informant 2:Not Recorded
If this is the correct one I can look for the parents' marriage and try to work back from there
Col