My name is Pierre Kayser from France.
I also have far ancestors with the name of "DORNBERGER".
Since I have studied the genealogie of my ancestors in Alsace, I have dicovered the great amout of peoples having emigrated in US during the 19th century.
It is always something fantastic to get in contact with far cousins.
Because yes, I think we are far cousins if your G grandfather was Florentz and had brothers with the names Lambert and Andre ( Andrew)
if their parents were George Dornberger and Catherine WENTZEL ....
they were fron Reinhardsmunster Bas-Rhin Alsace .
You can contact me here : firstname.lastname@example.org
I have a great lot of informations for you .....