People who think that Merrill would side with Solas are Wrong and should bask in their fetor of wrongness. Do you really think she would join up with a snide shithead who looks down on everything her people have tried to preserve in the intervening millennia?
Solas wants to “raise” the Dalish back to the way they were in the age of Arlathan. I don’t think it’s possible to do that without acknowledging the struggles and adaptations that were required to survive. Yes, Merrill wants information and history about the Evanuris. But I don’t think she’d want it at the cost of that sort of disregard of her people.