I am sure Proteek's true love for Sumu will be seen when Prchi refuses him categorically. I think he will start taking it out on Sumu and start differentiating between him and his own son. At least this is what I am hoping so that the heart break is not there. Anyway I don't think there are many step fathers who would love their step sons as their own if they have their own children, more so if the mother is not willing to give in to them. Here it is a fake step father. How can we assume he will be absolutely impartial? Even if he is the relationship between Sumu and Proteek will not be the same once Sumu comes to know he is not his real father. Everything Proteek does will be questioned by him. If, for instance, he tries to discipline him, Sumu will interpret it as Proteek's hatred towards him. Once Milsi comes to know he is the father, he will definitely want his kid back. This means Sumu will be caught in the cross fire. So the environment in which Sumu should be raised is definitely not the Dasgupta household.