You haven’t said precisely what denomination the family was. Pomeroy Church of Ireland lost its early records in the 1922 fire in Dublin. It now has nothing before 1876. Pomeroy Presbyterian church has records from 1841 onwards. So neither has any for the period you need.
There were no Black households listed in Glenburrisk in Griffiths Valuation for 1860, so they had either moved away or died out.