yesterday I had a phone call with my friend in Bremen. His mothers maiden name was Bahnsen. She died years ago. Last year died his grandfather, unfortunately I forgot his first name.
He was born in 1920 and my friend told me that his grandfather has mentioned direct family connections to Niebüll.
But we were not able to discuss this issue in detail, there were other currently very important thinks regarding his family to talk about.
So if the circumstances are better I will ask him for more details. At the moment it is not the right issue for him.
Hope that helps for the moment.
Best regard from Germany