"Anderson" was listed as surname of our father's original birth certificate, which was issued at birth. I think the certificate also listed Carl Anderson as father. This birth certificate was unknown to our father. Because our father's birth certificate was unknown to him and because his mother used her maiden name for his surname, he had a delayed issue birth certificate issued as an adult with "Schilling" as surname. He worked, served in the military, married, listed Social Security and had children, all under the surname of "Schilling".
However, according to his original birth certificate (given to him only a few years ago), he is an Anderson by birth, and has researched his birth-father's line back to Sweden. Technically, we are an Anderson family living under an assumed name. After finding his original birth certificate, our father felt it was too late to start calling himself "John Anderson" and had his name legally changed to "Schilling" to avoid confusion. He was an Anderson into his 60's, but calling himself "Schilling", and then in his 60's changed his name to Schilling. His children were all named "Schilling" on their birth certificates, so are legally "Schilling" although we are technically and genetically Anderson.
Because I am female, my brother is taking the y-DNA 37 marker test for me, so that we can clear up the confusion (hopefully) and confirm our surname is genetically "Anderson". I have applied him for membership under the hyphenated name of "John Albert Schilling-Anderson which is not technically his legal name, but highlights the link between our father's legal birthname and our current surname.