Hello,
First I want to say thank for this thread - it was the ONLY thing I could find anywhere on the subject of Udenhausen, and the discussion here did help my research a great deal.

For the record, I would like to mention there is a THIRD Udenhausen, located in Rhineland-Palatinate which was incorporated into the town of Boppard in the 1970s. I was also looking for SCHAEFER, knowing only that they came from Udenhausen, Prussia in the 1870's. As luck would have it, I have happily been able to locate my family origins in Boppard-Udenhausen.

best wishes,
Mary Ann