Hi Karen, I would say that Aisne is almost a no-brainer for them to have come up with it, but there is nothing giving any evidence for it over anything else in Picardie.
On the children's funerals, not too worried about it, already found in IGD, not like these kids had descendants. And the extra children in the census are a question mark, those censuses of the time have some errors in them, sometimes huge. No other trace of these kids found.
There is a large dearth of records for this family over here, I think I may have found one or 2 contracts involving Nicolas, and that's it. The daughter Marie Françoise marries and then disappears with her husband, inclined to think they left the area, either further inland or back to France.