The townland of Ballymaghroe seems to be split between three adjacent civil parishes (which are generally equivalent to Church of Ireland parishes). Killiskey, Moyne & Hacketstown
Parts of the parish of Hacketstown are in Co. Carlow
The dates covered for these parishes in the RCB Library are as follows :
Killiskey batp 1818 / marr. 1818 / d 1824
Moyne bapt 1879 / marr. 1846 / d 1879
Hacketstown bapt 1877 / marr. 1845 / d 1878
There's a few Perry individuals listed in the area on Griffith's Valuation and slightly later than Frederick's birth, including two William Perry listings in the townland of Ballymaghroe, although these could both relate to the same property and person. One of the listing is in Moyne, the other in Hacketstown.
Shane