1871 - Kilsyth, Stirlingshire - FindMyPast shows that John was with Mary and the children too.
John Crawford 35 Slater
Mary Crawford 27
John Crawford 3
James Crawford 1
Lilley (?) Crawford 10 all shown born Glasgow
1881 - Boarders with a family named Canboy in Alloa, Clackmannanshire
John Crawford 46 Slater born Glasgow
Mary Crawford 36 Housekeeper born Port Glasgow, Renfrewshire
John Crawford 14 Schoolboy born Glasgow
Margaret Crawford 3 born Edinburgh
According to the birth certificates of John (b.17/10/1867 Glasgow), James (b.8/11/1869 Glasgow) and Margaret (b.6/5/1878 Edinburgh) their parents were John Crawford, a Slater (Journeyman) and Mary Morrison - different marriage date on each one which are 19/1/1867, 4/2/1867 and 19/1/1866 all in Glasgow!!! However, there is no marriage on SP or familysearch between a John Crawford and a Mary Morrison anywhere around this period.
So, John Crawford is born ca.1835 Glasgow BUT with no marriage found to Mary Morrison no idea who his parents were, nor hers of course. Being a slater journeyman meant he had to travel around and obviously his family went with him.
The only slater I can find in 1891/1901 - this time living in Dumfries - matches John's details but the wife with him is named Margaret (Maggie) - Mary could have died and he remarried but impossible to trace in deaths index because Crawford is such a common name and they constantly moved around. Even trying to find John's death after 1901 is difficult - no likely John dying in Dumfries either.
Best I can do.
Annette