Hello, I'm not quite sure, if I can help you. The town of Geestemuende, where Johann Wetjen was born, is a part of the city Bremerhaven in Northern Germany. My grandfather Johann Christoph Wetjen was born in 1875 in Appeln close to Bremerhaven. This could be a relationship, because usually the name Wetjen is originated in a town called Weyhe close Bremen, which is about 50 miles from Bremerhaven.
So if you are interested in some more informations don't hesitate to contact me.