Hahaha, i had forgotten about the skyrim roleplay. Ok, i do recall you. 

Alara was never destroyed. It did get ravaged by the uncontrolled mana that were released when the shards were smooshed togather. Nicol Bolas actually healed Alara in a way when he orchestrated the merger of the shards. Of course he wanted to steal the mana for himself. Evil intentions uncertain results. Now, one does not have to be a planeswalker the walk from Bant to Jund. There are no longer the 5 shards of Alara there is just the plane of Alara. Elspeth is troubled because Bant is now subject to Deceit and ambition unlike before the merger.

Also, as for what you think about the story of this roleplay. I believe you are correct. That does seem to be the original intent of the creator, the silent The Silent Type. I However am thinking of setting this years after the events of Avacyn Restored. Tibalt has returned a little older and much more powerful and aimed to take the plane from the Ancient Sorin Markov.

As for the last name of the child, I have no idea. I do not know the naming rituals of Bant, Theros, Ravinca, or Isperia. It is possible the female gives up her name for her husband's like European cultures do. The names could be combined to proclaim both proud lineages. It is also possible that the child would take the name of the parent who he or she spent the most time with or took the most abilities from. I could also see a female child taking Beleren while a male child would take Tirel. It is up to you. Planeswalkers seem to be a part of a culture all their own.