My ancestor is born at Bagnolo between 1839 - 1841, and i found a lot of brunofranco living in Bagnolo ... so it seems that the real surname of my anscetor is brunofranco , who become Brun-Franc in France.
Yes, I'm sure surname exact is Brunofranco. It is composed from two names of baptism: Bruno and Franco. In south Italy there are surnames only Bruno or only Franco , but Brunofranco is much rare one, and exist only Piemonte region. Good luck, suanj