Is this Frederick in 1911 census:
2 Epworth Lane, Rathmines & Rathgar East, Dublin
Frederick Champion, 38, domestic coachman, born Dublin City
wife Margaret Champion, 28, married 9 years, 3 children/3 living, born Meath Co.
dau. Lilian Champion, 8, scholar, born Dublin City
son Frederick Champion, 7, scholar, born Dublin City
dau. Margaret Champion, 4, born Kerry? County
All are listed as Roman Catholic
Marriage certificate for Frederick and Margaret should list his father's name and occupation. There are a few other Champions in 1911 Dublin census which you can search here:
www.census.nationalarchives.ie/search