Joe:
The RC parish for Maddenstown would be Newbridge. There is a gap in records from 1795-1820 https://registers.nli.ie/parishes/0721 I searched the subscription site Roots Ireland and did not find a baptismal record for Martin probably because of the gap. Also, did not find a possible marriage record.
I did find seven baptismal records for Martin Carr and Esther Dowlng. Let me know if you do not have this information. I did find a June 17 1821 marriage record for Martin Carr and Esther Dowling. The RC church was Monasterevin. Both Martin and Esther lived in Kildoon. They later moved to Maddenstown by 1826.
I also located an 1826 Tithe record for Martin Carr in Maddenstown. He was leasing about 10 acres.
http://titheapplotmentbooks.nationalarchives.ie/reels/tab//004587406/004587406_00426.pdf
Roger McDonnell