Hello
I don't know whether it helps or not but in St. Ninians, the 1851 census has a HODGE family with parents John and Margaret with children Alexander, Margaret, John, James, Christian, William, and Helen. The father John is listed as aged 46 from Raploch, Stirlingshire and a farmer.
Could this be your John and Margaret? In which case it might point more to the 2nd birth that you've listed.
Let me know if you want the full details of the census.
Isobel