It’s always great to get a new spelling variant. My great-great-grandmother’s maiden name was Franciska Bieger. When her daughter married in Hancock County, Illinois, in 1905, her name was written as Francis Kabücher. That was a variant I had not thought of: Kabücher. It also reminded me that Bücher could be a variant for Bieger as well.
Was the end of your relative’s first name turned into part of their last name?