I have a lot of genealogy listed for doub, daub, doupe, doube, I don't know if it is what you are looking for.
www.geocities.com/judydrysdale
Is John Doub's father. Johann Michael?
Is so there was one sibling, Charles. John's line I think died out, after his son died and then he died..
check into my site, you might find something there.