The details of the baptism on Ancestry are
Patricius Colbert
Baptism Age 0
Event Type Baptism
Birth Date 1841
Baptism Date 6 Aug 1841
Baptism Place Tipperary, Carrick-on-Suir, Ireland
Diocese Waterford and Lismore
Father Patricu Colbert
Mother Marg Sheehan
There's also the original image but it doesn't give any more info than the transcript and is very hard to read, so mother's name may not be transcribed correctly. What mother's name does RI have? I have two possible other names for her (from Patrick Colbert marriages I found) Condon and Harrington but they were both married after 1841.
I've made a note of what you've said about other siblings (finding them could really help if they came to England too and are on censuses) and the possible baptism of Margaret, and I'll investigate them when I do my 24hr blitz.