Their church marriage record in Canada should include at least the fathers' names and possibly both parents names.
Their obituaries and cemetery records are additional sources that may include their parents names, even their church burial record or civil death record.
What were their dates of birth? There are no civil registration records in Ireland before 1864 and no surviving census records before 1901. Church parish records that may survive for Upperchurch for their religious denomination may include their baptismal records if they were born there and didn't reside there before emigration.
Do you know what their religious denomination was?