Who is Bara Rani from The Home and the World and what is their importance?

The Bara Rani is Nikhil's sister-in-law who lives with him and Bimala at the Rajah's house. Her strained relationship with Bimala frequently causes tension in the household. The Bara Rani often uses Nikhil to obtain the material things she desires, and though Bimala constantly complains about her sister-in-law, Nikhil is tolerant of her because he pities her lot in life. The Bara Rani continually mocks Bimala's friendship with Sandip.