My grandmother was Lois Dinger, daughter of the Dinger who started a candy company in Detroit. I will post my great grandfathers first name as soon as I get it.
Lois Dinger's father or fathers' father emigrated from Eichstetten Germany. My father (Robert H Gray, JR) and I (the III) visited Eichstetten south of the Black Forest in the 1990's. The town monument has a bullet hole in it and Adolf Dinger rests in the local cemetary, killed in world war II. His brother, I think, was a German POW.
I may be able to find and scan a the photos of the present Dinger family in circa 1990 and Email them if you want. But I do think that my Great Grandfather Dinger is one of the four you are looking for.