Can a Muslim do nikah with her wife’s niece (Bhatiji) while his wife is still in his nikah and is alive, both niece and aunt can be wives of same man? In the same way can a man keep banji and khala as wives at the same time?
Answer:
It is not permissible for a man to a woman and her paternal or maternal aunt at the same time. (Hidayah p.308 v.2)
Saaiduna Abu Hurairah 
narrates that the Prophet of Allah 
said: “One should not be married to a woman and her paternal aunt, or a woman and her maternal aunt, at the same time.” (Sahih Bukhari p.766 v.2)
Only Allah Knows Best
Mohammed Tosir Miah
Darul Ifta Birmingham.