Sivir's history.

It's not explicitly stated how Sivir is related to Azir, but it's stated that she is, "the last in the bloodline of Azir." Interesting choice of words, but we know she is of course related by blood to Azir. Their blood bond is strong enough that her blood was enough to resurrect him. And being related by blood you have to wonder how is Sivir alive if Azir's wife and children perished in the blast that killed everyone in the city. It could be that Sivir is descended from a sibling of Azir's. Said sibling could have had the legendary boomerang in their possession and spell shielded the blast that killed everyone else.

I know it's a far stretch, but her boomerang also serves as the key to opening the tomb of the emperors. I mean sought out because of the weapon right? It wasn't a coincidence that Sivir was the owner of the blade and Cassiopeia knew it.

Throughout the years, maybe Nasus has been keeping an eye on the blade and whomever wields it. Nasus was the one after all, who sealed Xerath and Renekton away. It's said on Sivir and Nasus' page that they're both friends; maybe that's how they became friends?

What do you guys think? I really want to see more of Sivir's history and how she is related to Azir. Is it possible that one of Azir's children survived the incident? Or is Sivir descended from a sibling of Azir's? If she is, why didn't that sibling resurrect Azir sooner?