I don't have any more information than you do on Peter Drehmer's ancestors but I have been trying to find someone in Peter's family for years, hoping that someone in that branch of the family had more information. I would certainly like to get more information on Peter's descendants. If you are interested, in information about his siblings, I can certainly help. Peter's sister, Mary, was my great grandmother. She married Jacob Wolf. They had 15 children, including my grandfather, Peter. There is a section on the Drehmer family in a Wolf family history book that I have.
I certainly look forward to hearing from you soon.
By the way, have you ever heard the name 'Ortwein'? Jacob Wolf's eldest sister, Katherine married Conrad Ortwein. I am trying to find their descendants.