Zehr holds citizenship at only one location in Switzerland, that being Niederstocken.Niederstocken belongs to the church parish of Reutigen.If you have access to a Family History Center, those records have been microfilmed, and you should be able to locate and follow the ancestry of the family.
Marti is a very common surname, and holds citizenship at 42 localities in Canton Bern.Eggen held citizenship at 20 localities, one of which is also Niederstocken.
If your Marti and Zehr married in Switzerland, then either their marriage and/or baptisms of children may list where she was from, so you would know which locality to search.
Did they also die in Tuscarawas County?Have you located them in church records there?Some of the Tuscarawas County church records in the death records list the birth locations in Switzerland.
I have MARTI in Switzerland at Rüeggisberg, and it was 150 years after I lose that surname before my ZIMMERMAN family moved from Wattenwil, Canton Bern, Switzerland. http://home.netcom.com/~fzsaund/marti.htmlhttp://home.netcom.com/~fzsaund/marti.html