User blog comment:FairyRaven/Fairy Tail Chapter 307: The Legion of Hungry Wolves, Review and Commentary/@comment-4556903-20121113021824

Yukino cannot be Edo-Lisanna but I think that Mashima is foreshadow something for Yukino. Maybe she will met her sister at the end of the arc or she could be related to the Strauss sibling like she is their cousin, that could be a good reason why her hair colour is white.