The Johann (John) Casper Walthauer/Waldhauer family is featured in "Georgia Salzburgers and Allied Families" p. 350-355. Shows several generations of descendents. One of his 6 children was Margaretha (b.1719 who may be Margaretha Barbara?) married William Ewing/Ewen. Johann Casper was b. 1690. "Wife's name not known". "Settled in Ebenezer, GA about 1742-44". Three of the children are shown as having migrated on to Penn. There are also significant references cited for members of this family in "Ebenezer Record Book, 1754-1782" and in "The Germans of Colonial Georgia"
It may be that the Margaretha Barbara Waldhauer you refer to was a second wife of the Savannah immigrant, Michael Burkhalter. However, it is my believe that years ago researchers found the marriage record of 1703 in Lutzelfluh, Switz. of another Michael Burkhalter to one Barbara Walther and incorrectly assumed/reported it to be first marriage of the Savannah immigrant. Perhaps some are now considering this Barbara as the second wife? I found this same marriage record several years ago in Canton of Bern Archives at the time I found the baptismal records of the children of Savannah immigrant, Michael Burkhalter and his wife Adelhiet Kobel. The baptisms for the two couples' children overlapped proving there were two different Michaels. I believe further research is needed to prove name of Michael's second wife. Your information that the Waldhauer family was taken in by Michael Burkhalter offers a possible avenue to pursue. Thanks for posting it. Regards, Carlton Wood