Kanic said:
Nyaah, I don't think so. I think it's Hiro foreshadowing somekind of "Mirajane taking the bullet for Yukino" momment, which would make a lot more snese if Lisana was dead.
Mira already took a bulletexplosion for Lisanna. So if you disregard the chance of them being relatives, it would be more like giving Yukino a chance to experience "sibling love"