Start with the books: Germans to America and see if you find them there. You can also look at immigration ships lists at the NARA website (including Castle Garden before Ellis Island opened). If you live in a city where there is a NARA regional center you can look at the US census index to find where someone with that family settled. That index may also be on line at ProQuest and Ancestry.com. Public libraries usually give free acess to one or both of them. Go o familysearch.org and search with the surname Grossbach with the search offered on the home page. The hits will tell you where some families with that name lived in Germany, Bohemia and Austria. Understand that some people who identified themselves as Austrian could have been from Bohemia. Likewise, some people who are identified as German could have been from Austria. Karen