Just to be CLEAR for the nth time, Sahiba NEVER informed Angad about the baby... neither when she was pregnant nor after the birth...Neither once in 6 years nor now when they came face to face..
If the phone call is what some ppl are pointing at, None of us heard what Sahiba said in that call... If she had told him about the baby in that phone call, then why is she not surprised now that Angad doesn't know that its his baby? How is she able to continue to hide the baby's paternity truth from him??? 
Spare us with the predictions that they WILL show such one or multiple phone calls ( where she tried to inform him) ... We will talk about it when such scenes comes in the episode....
All in all, Sahiba hid about her pregnancy and the child for 6 long years and is planning n plotting to continue to do so...She didn't give a chance to Angad to do the responsibilities of the father or be in the life of the kid and then laments that he was not there to do any responsibilities and then handed out the fatherhood to this person with whom she was living at the time of delivery ( faking as his wife) saying he did all the responsibilities..
Yeah Angad should have had superpowers to imagine Sahiba was pregnant and should have guessed the date of delivery and should have done the responsibilities towards the child and mother without knowing that they existed.. Its his fault that he couldn't be a antaryami..LOL...