Hello Luis,
I am the 3rd daughter of Jose Manuel Ariano Eckardt, first son of Jose M Ariano and Eva Eckardt.
I came upon your message also looking for your great grandfather.
Contrary to your spelling, in the genealogy of the ARIANO-ECKARDT family the name of your great-grandfather is written as:
Frederic(k) Wilhelm Eckardt Dehayes.
And, yes, there are several Eckardts still living in Alsace. As I live only a mile away from the Department of Haut-Rhin, I think I can find out a bit more.
As it is not usual in the German- or French-speaking cultures to use a second last name (contrary to and as in the Spanish & Latin American cultures by adding your mother's maiden name), I need to have the exact name & spelling of your great-grandfather registered name.
Therefore, if you have his Wedding Act from the City of Strasbourg, kindly sent me a copy, [PDF-file scanned as an attachment] allowing me to contact directly the Registrar or the "Standesamt". This will definitely give us the connection with the name Dehayes: is it his mother's name or is it this of his wife? Whom did he marry in Strasbourg?
Thank you for contributing with this information and I can probably help you further as I have been also constructing the genealogy tree for the Arianos descendants of Joseph.
Best regards,
Beatrice-Helena