Hi Suse
The 1881 census has a Murtha family living in Monkwearmouth Shore, Sunderland (RG11/5006 160 p93):
Michael Murtha, Head, 62, Labourer to blacksmith, b. Ireland
Ann Murtha, wife, 58, -, b. Ireland
Barnard Do, son, 27, Plater's lab,b. Ireland
John Do, son, 24, Do Do, b. Durham, Sunderland
William Do, son, 22, Do Do. b. Durham, Sunderland
There is a Morrow family living in Sunderland, (RG11/5000 42 p78)
William Morrow,Head, 54, Boiler maker's labourer, b. Durham, Gateshead
Eliza Do, Wife, 47, -, b. Durham, Sunderland
John Do, son, 27, Baker Journeyman, b. Do, Do
Henry Do, Do, 19, Boilersmith apprentice, b Do, Do
William Do, Do, 17, Do Do, b. Do, Do
Eliza Do, Daur, 14, General Servant, b. Do, Do
Joseph Do, Son, 12, Scholar, b. Do, Do
Elizabeth Do, Daur, 10, Do, b. Do, Do
Margaret Do, Do, 8, Do, b. Do, Do
Anne Do, Do, 6, Do, b. Do, Do
Are these the families that you are asking about?
All the best
Gobbo