Hello,
no I do not know anything about your ancestors. I found 1 Mühlenberg in Baden-Württemberg. Near by Sulzbach/Kocher. The church books are available at LDS. Look at Familysearch, Library, Library Catalog,Placesearch, give in Sulzbach and take: Sulzbach (Kocher, OA Gaildorf). This should be the right one. Here are the lutheran church books from 1588-1915. You can order it to the next LDS office near by your home town.
Good luck,
Margarete