Odd with the surnames for wife
Did Martin show as a widower in 1871 on the original image?
An online tree includes a marrige for a Martin Wallace to a Mary Mulcarron on 2 Oct 1864 in Inverin, Galway, Ireland - source details not included.
Some children's births showing all in Govan, with a father Martin Wallace, include:
Mary Wallace b. 7 July 1865 Govan - mother Mary Mulcarron
Patrick Wallace b. 4 September 1866 Govan - mother Mary Mulcarron
Henry Wallace b. 12 July 1868 Govan - mother Mary Cairns
Martin Wallace b. 13 March 1870 Govan - mother Mary Murphy
Margaret Wallace b. 3 October 1871 Govan - mother Mary Cairns
William Wallace b. 3 January 1873 Govan - mother Mary Mulcarron
Bridget Wallace b. 20 August 1874 Govan - mother Mary Mulcarron
Margaret Wallace b. 6 October 1881 Govan - mother Mary Mulcarron Wallace
All birth indexed entries on
https://familysearch.org/searchLorraine, this must be your family with John, your g grandfather already born in Govan 1881 (sure you have this but just for background here):
Martin Wallace 35 Ship Yard Labourer b. Ireland
Mary Wallace 30 b. Ireland
Mary Wallace 16
Maggie Wallace 11
Bridget Wallace 7
John Wallace 3
Arthur Donnally 58 boarder Boat Yard Labourer b. Ireland
Would guess Maggie aged 11 must have died shortly after this census and Mary pregnant already to be able to call the October 1881 b. baby girl Margaret too....can't easily see the death though so far in 1881
Monica