Thanks for your reply to my query. I had almost given up ever receiving an answer. Your line is most interesting!
Heinrich Jahnke could be an older or younger brother of my Fredericka Jahnke. His wife, Wilhelmine Krueger, was about seven years younger than my great-grandmother (born 1826).
Also, my Jahnke ancestor moved directly to Canada in 1856
(about 25 years earlier than your ancestors immigrated to MN and WI. However; since they all came from Bandekow, there is a great possibility that they somehow could be related...if not brother and sister, then perhaps cousins.
I really do appreciate your sending this information. Now if we could only discover the parents of your Heinrich Jahnke...we might have the best clue of all. Do you know who they might be?