As a Swiss name, from the "sound" of it, I would guess that Fiana is a Romansh name. If the Fiana from your family tree was living in the Grisons (Kanton Graubünden), this would be all the more likely.
I cannot prove it, however. Google shows that there are people named Fiana living today in Switzerland, but probably very few.
Because this message is archived you cannot respond to it.