Based on the given names of these individuals -- Christoffel, Friederich Wilhelm and Frans Heinrich, I can say with 95% certainty that they are NOT from Schwenningen. These names rarely if ever appear in Schwenningen. In fact, I'd say they are probably not from that region, but further afield.
At least you know where they are NOT from.
Best of luck to you. Sorry I was not able to help.