Unfortunately you need to know the town of origin in order to conduct any research in the German records of that time period. You need to exhaust all the possible sources of that information in US records first, along with determining where their friends and neighbors originated. Here are some suggestions for how to find town of origin in Germany:
https://familysearch.org/learn/wiki/en/Germany_Locating_Plac...https://familysearch.org/learn/wiki/en/German_Research:_Hans...