Lamar,

Looking at the older Census there was a George Seas who had a male child in the 5-10 yo bracket which would have matched your William S. Seas approximate age. No other "SEAS" listed had male children in this range. Also they were from Pennsylvania which matches the descendants profiles. I happened to be looking into this family because Wm's 2nd GGSon, James Seas, is my 3rd cousin from a different line (Seas<Lee<Newton) I also believe this could be the Wm Seas who served with the Union Army from Pennsylvania and received an Invalid Pension following the war.