I've always seen Flemeth and Morrigan as THE mother daughter duo with a twist, that in the beginning the daughter does not trust the mother, but eventually she'll come around. And together they'll be behind a chain of events that will change the world. And this might sound sexist but the Bard had it right when he said that hell hath no fury like a woman scorned. Solas wouldn't be a match, even remotely.
How about no?
My warden make them fail when she rejected the ritual(which is a legit path if you have forgotten,also Bioware internal canon)
Chains of events are started by others Flemeth/Morrigan are more like watchers and nothing more.
The Warden,The Inquisitor,Hawke,Solas,Corypheus,The Architect,Anders,Isabela those are the persons who influenced the 3 games as far as i'm concerned,Morrigan did nothing,Flemeth did nothing to alter the world aside from giving powers to Solas and take the Warden to try to use him/her for the ritual which is not even mandatory.
Flemeth/Morrigan only preserved ancient things (or try to) until now,this was their purpose.
While Morrigan can become pretty much a non factor in both DAO and DAI.
Also Solas proved to be more powerful than both of them by now,and yes he is a trickster he used the Inquisition for the whole time and maybe he is just playing the part of a guilty dude,he killed Felassan who was a formal friend with no regrets and by showing his more dark side.
He is the true Fen harel not like FLemeth who is just an human with a wisp of Mythal.
So i would say that FLemeth is not a match for Solas not even remotly not the contrary,in fact evidence of the game stand with me,since he pretty much finished her without any efforts.