I have found that some members of my famlly used this spelling of their name in Germany and here. They were Jewish, so may not be connected to your family. There was a Joseph Senger born in Konitz, now Chojnice, Poland, in ca 1780. His son, Louis, was born in Schlochau West Prussia , now Czmon, Poland in ca 1815, dying in New York in 1884. Louis had two sons, Robert and Emil, both born in Koeslin, West Prussia, now Koszanowo, Poland. Both ended up in New York. Emil became an opera singer of some renown.
I would be interested to know if you found any traces of this branch of the family.