I do not know how much it will change, but seeing as one of the reasons they seemed to possess to hate each other was their "difference", then perhaps proving to them that nearly all of their blood is at least somewhat mixed would encourage them to reconsider hatred along racial lines...

[It relies on... Them being logical about it, in them believing in her methods, on many things, but]

I hope.

[But wait-]

He made you an offer?