Hi Ash
Could this be your Crawford relations living at 40 Ferguslie in Paisley Low, Renfrewshire, in the 1841 census, given that John's occupation was weaver?
John Crawford, age 25, Cotton Handloom Weaver, born in Renfrewshire
Jean Crawford, age 20, born in Renfrewshire (Jean being a diminutive of Janet in Scotland)
John Crawford, age 3, born in Renfrewshire
Mary, age 1, born in Renfrewshire
Did your John Crawford die in Casino, NSW?
Cheers,
Rodeo