My wife is a Fehlberg. I have found out so far that these Fehlbergs migrated to Australia from an area of Prussia that is now in Poland. No doubt other went to USA . I have a contact over there who is also interested and may be able to help. He is Hauke Fehlberg:
"Hauke Fehlberg" <hfehlberg@datacomm.ch> and he understands English perfectly. Drop him a line.
Frank Winston