Ranbeer knows about natasha below u can see the following proof that ranbeer knows...
First Proof:
At the Kabadi tournament Chunnu won because of saying the mole that kanya had in her back. Ranbeer got angry how he knew it and thats why he lost.
(Earlier in KIT u can see that Ranbeer and Kanya were in the same room, while ranbeer saw the mole on her back from he remembers that it was from natasha)
Second Proof:
Remember when Ranbeer was looking one morning for Kanya he talk to his jiju and harpal to ask where she was. He search upstairs and that old lady touched him ahaha than he went ask pooja and she said that kanya left with pammi dhi mammi and rajesh khanna to the doctor.
(He was wondering why she went away with pammi dhi mammi and rajesh khanna, the not showing scene claims that he went to search her and follow to the doctors place and when natasha was acting angry maybe because she saw ranbeer sneaky somewhere the area)
Since these episodes Ranbeer is in love with kanya and he is also concerned about natasha.
I want to know if people agree or disagree with me.