For Peter Phelan M 1854 (exact), Abbeyleix RC parish, Co. Laois, I found 1 rcd. A view of the detailed rcd SHOULD show the bride's name as well as their parents' names. This info is useful in identifying earlier B rcds, and their parents' marriage records.
For Cat(herine) Carroll M ditto, I found NO matching rcd. This casts doubt on the validity of the finding for Peter.
Your DOB and parishes for the Phelan children correspond with rcds in the current database.
For Peter Phelan B 1820 +/- 5 yrs, Co. Laois, I found 1 rcd, 1822, Aghaboe RC parish.