My father's surname is Seitz (well, it was Seitz before he married), we're living at Oberweier. I found this message board by chance when I was doing some investigations about my family. We also have got the book mentioned by Darrel Hunter. I can retrace my father's family until Benedikt Seitz, born December 19, 1757 in Heiligenzell. He is also listed as a carpenter. The book is only about people who were living at Oberweier so I can't go back farther. There is nothing said about Benedikt Seitz' parents so I can't say if Johann Georg Seitz and Benedikt Seitz are related.
One of Benedikt's sons went to Amerika, his name is Lukas Seitz (*16.10.1808). Five of his grandchildren also went to Amerika.
Any answer would be great!