After watching yesterday's episode, I don't feel that Saudamini and Kanchan are related by blood. I mean Saudamini is not Kanchan's aunt or anything like that. I also don't feel that Kanchan is Prithvi Khanna's daughter or anything like that. What I do feel is Kanchan's father was either Prithvi's business partner or was working in his office. Something happened for which Prithvi held him responsible as per his principles, like some illegal scam or some such thing because of which Kanchan's father committed suicide and her family was ostracized. They were treated with contempt. And that is what is driving Kanchan for revenge.
With Saudamini, I think she is a woman scorned. She wanted Prithvi to love her, and he rejected her. Maybe at that time, her way of living was so different that he no longer recognizes her in her current avatar. It is this rejection that is motivating her to ruin his family. And she has spent her life to learn the craft of tantra to take her revenge.
Most probably these two came together for this payback. Like the saying goes "enemy of my enemy is my friend" or "my enemy's enemy is my friend". The thirst for revenge is the only thing that they share and that is what is making them work together.
I am finding the story picking up pace and getting interesting. And am also happy that the slot will be changed to an earlier time. 😃