My two cents, Badal will tell Nik about Sonali and he will hide this from Pallvi. Dadi will try to bind them legally together. I think that's what Nik wants too to tackle Ranveer.What will happen when Pallvi knows about Sonali and Nik hiding, she will again feel cheated and then the whole drama will start again.
Seems Nik and Badal have same amount of sympathy towards Sonali.
Already Sonali is "bechari" for Nik, and after coming to know about her present state, his sympathy may increase exponentially.