Ok so the audience, us, knows that Raghu is Sid and Sid is Raghu. Hence, Sid is trying to confuse Shabnam. Shabnam as we know will out the news about Raghu being a look a like of Sid and that he is not Sid. Therefore, Sid is still known to be dead and that by DD. So DD is once again arrested. But then we will have Kritika come and show proof to the police that her brother Sid is in fact alive somewhere. So all this is a part of Sid's plan to confuse and ruin Shabnam. But no one other than Pinto knows the truth about Sid and that he is pretending to be Raghu. So what proof and how does Kritika get it?
I have this feeling that Sid has either left those clues at his house for Kritika to find or he has indeed told his family or at least Kritika the truth. He might have gone to those which is why he was late and hence gets beat up by Roshni. I keep wondering how she got the clues and how she came to know that at that very moment DD was going to get arrested. Or Sid do it in purposefully because he knew something like it was going to happen. And Kritika only actually had come to the house to tell Roshni that Sid is alive.
As per the segment, Roshni is very happy to know that her Sid is alive somewhere. If she is happy just knowing that, wonder how happy she will be to know that all this time the person she thought to be a look a like was actually her Sid and she was spending all this time with him and not Raghu.