His father, Paul, died in 2002 I believe.
From an obituary:
Paul M. Szumiesz
Served in the Air Force during Vietnam conflict
Paul M. Szumiesz Jr., 56, of Manchester, died on Jan. 24, 2002, at Elliot Hospital in Manchester.
Mr. Szumiesz was born in Manchester on Dec. 13, 1945, and educated in local schools. He joined the Air Force during the Vietnam conflict, and later worked many years as an optician for Kollsman Instruments. He had been a communicant of St. Patrick Church in Milford.
Mr. Szumiesz was predeceased by a brother, Glenn Szumiesz, in 1980.
He is survived by sons Ryan Szumiesz of Milford and Sean Szumiesz/Allard of Montreal; and, Marcia Szumiesz, John Pelczar and Dave Pelczar.
Donations in memory of Mr. Szumiesz may be made to New Horizons, 199 Manchester St., Manchester, NH 03103.
The Cremation Society of N.H. is in charge of arrangements. "
I'm sure you already know that, but just in case...
It is possible Sean does not want to be found or re-associated with the Szumiesz family. We all know how messed up our past efforts to stay connected have been.
If you don't mind, what is your relation to Anthony C Szumiesz (DoD 1999). I have a family member that has been tracking via Ancestry and she might have more information to help but I would like to make sure the relation is sound before passing that information on.