I just did a search for "Erdall" and eventually found this message board. My great-great Grandfather was also born in Norway. He came to the United States and changed the family name from Erdahl to Erdall. I don't know if you will even see this due to the age of your mesage but I'll ask my parents what they know about "Hans". If I find out anything, I'll post it here. If I don't here from you soon, I'll E-mail you directly.