1851 census has numerous Reddings born in Cheshunt in the years just after their marriage.
But these could be children of John and Margaret , or couldbe nephews or another relation.
If you have checked Cheshunt itself for their christenings, then it might be worth trying neighbouring parishes.
Or, of course, they may not havebeen christrened!
Would be worth checking marriages for any that married after 1837 to see what fathers name and occupation is.
I alao cant find a death for Margaret. That could be bring clues - if she dies after John, then informant could well be a child. In fact she may even go to live with a child after John's death.
So that is something to work on.
If people have put children for this couple into their trees, then why not contact them and ask what evidence they have? If they have seen the PR somewhere for the christenings, and can tell you where and when they took place,then you have your info(best to check it out still), but if they havent, and cant provide you with any evidence as to why they think the children are of this couple, then just forget about them.