When Nandita explained her plan to Upen and Bankib, they seemed pretty impressed, so I'm guessing it doesn't stop at simply getting Rudra kidnapped.
Maybe they found Rucha, and made her agree to work for them
Then they gave her Rudra's clothes and jewellery, and gave it to Rucha, and probably told her about who everyone is and stuff
And now, once she's in the house, they'll make her do their bidding, making Baba hate Rudra and mistrust her
If Payal were replaced, there would be some news about it, or it would be mentioned that Rudra will be played by Rucha, not Payal
So I think that Rudra is still captive, and Rucha, evil, has come to do Nandita's bidding
What do you all think?
Yuks