Hello, Matthaeus Seitz was a citizen (Buerger)of Heiligenzell. His son Johann Georg is listed in the Oberweier book as a carpenter. Georg is married on Jan 13, 1727 to Catharina Kaufmann daughter of Jakob Kaufmann a carpenter from Heiligenzell, and Maria Magdalena Speckhammer from Hussen. She is one of five children. Georg and Catharina Kaufmann had eleven children. Sebastian is listed as being born Jan 19, 1730, married 1755 in Heiligenzell to Maria Magdalena Baehr. There is a little more on this family in the book which I have.
Let me know if you want more on Sebastians siblings, or Catharina Kaufmann's family.
(I have ancestors in Oberwier, Heiligenzell, and Diersburg.