What a sweet heart she is! My guess is that she's a berner with some different markings. It is hard to tell what the markings are when they are still pups. Rileys changed ALOT as he got older. A good bit of the white seem to disappear from his legs and from his face. He also had a white spot on the back of his head and it went comepletely away.. If she is a mix, I still think she a more Bernese than anything else.
If you cant find the family are you planning on keeping her? They really are fantastic dogs.
You will love her! You probably already do. lol