Chris: After many months I finally checked and received your messages... sorry about that. No, I do not know anything about Peter's siblings... haven't a clue! You mentioned a William Sifferman and by chance, Peter and his wife, Eva K. Hombach, had three children---named Frank, WILLIAM, and Mary. Peter died in Victoria, Texas about 1851, but the reason he was in Texas and where he came from remain a mystery. I did receive a note from a Phillipe Sifferman in France who has been working on this line, but I don't know if there could be any connection. We'll see. Sorry for the long delay in answering... keep in touch.
Iris