Try newspapers of all the areas in which ggf and his parents may have lived. Many are online. I have used GenealogyBank to good effect re details of ancestors and their siblings, etc.
In addition to newspapers, try the libraries of the cities and towns in which and near which they resided. Libraries often have resources beyond the official sources.
Look for state censuses in yrs other than federal census yrs. I believe New York had censuses in off-years.