Two Sisters At A Time?

It was shocking for me, I can't imagine that in a Muslim society, we can see this kind of example before. A Muslim person named Qurban was married to his cousin Shahida, his younger sister in law Noshaba was living in his home, after death of her parents. The family was living in a rented house. With the passage of time Qirban and Noshaba fall in love and decided to get married, but Qurban was also deeply in love with his wife Shahida and he was not ready to leave him. He decided to have a talk with his wife and result was the permission of his wife to have living relationship with her younger sister Noshaba. Now Noshaba was also living there as an illegal wife of Qurban. After few months Noshaba got pregnant, and she was not ready for abortion. Three of them decided to have the shelter  of Nikah to legalize the birth of that child. Now Qurban was in search of a new house on rent. On the other side his wife was also expecting, while shifting to their new home.
At new home in the other part of the city, they were feeling safe and during this time Qurban made his second marriage with Noshaba, concealing the real relation with her. The secret was open after three years when one of their old neighbors lady met them coincidentally. Some neighbours raised the voice, but he stated that Shahida and Noshaba were cousin, not real sisters. He also challenged his neighbors to prove that both ladies were real sisters.  
No one have the time to involve in such matters. Now both sisters are in old age having more then thirteen sons and daughters. Their two daughters are married and they have engaged their elder son also.