Personal headcanon after all that fuss:
For a time, Lavellan returns to her clan, which now lives in the city of Wycome along with a coalition of human merchants and the city elves, in supposed harmony. As First to her Keeper, it would have been her role eventually to keep the ancient knowledge: Knowing the truth, or something far closer to it than the Dalish once did, she does the only thing she feels it right. She tells it. To the Keeper, to her clan, to all the city elves. She grants them this knowledge carefully, but for them to do with as they see fit, hoping to turn potential recruits away from Solas or the Qunari.
Unlike Solas, Lavellan does not believe in hiding the truth: And being the Keeper's first, and a hero of Thedas, she is in a far better position to spread it than he was.