Just by supporting Sahil and of course it is hard to deny her love for Nakul being the biological mother, she is not aiding the truth. She is just reconciling herself to accpeting Sahil's new reality which is Tripti. SO Damini's role is passive where it shouldn't be yet resentful towards Karan and Ganga where again it shouldn't be.
I am still not convinced that Damini is handling the situation without bias for Nakul. In the past also she had picked up a major fight with Ganga over Nakul and had asked for the custody of Nakul back through the lawyer. Post leap the mothers like Tanya and Damini are being shown as biased towards their children. This is not the culture that Tulsi had taught her Bahus.