Unless it is bugged, there is not.
On PTS, I didn't tell her secret.
On Live, I told the secret.
The same thing happens regardless, and she doesn't even mention that I told the secret.
I don't have an answer to that question, I suspect it will happen whatever you chose to do. I just want to say that I was pleased to see a Motierre in ESO, as there were descendants of that dynasty in both Oblivion and Skyrim involved in some way with the Dark Brotherhood.