Is Nitya Payal's sister or cousin?

I was just thinking whether Nitya/ Durga is Payal's cousin or sister. Possible that the blind man could be Durga/ Nitya's father, ie, Payal's uncle and that is why Shaurya didn't recognise him. Also in the FB scene where Payal and her parents were showing her drawings to Rajnath, a particular drawing where she was showing both Goenkas and her parents and herself as my family, I don't remember seeing any drawing of a sister. There were the 4 Goenkas and Payal's parents and a little girl( the girl could be either Payal herself or Nitya)