cuz saloni kept nahars death from the family and she brought amrit (nahars lookalike) to pretend to be nahar to save the family from jiji's clutches
(jiji took over the property and killed nahar and put nahars signature on the property documents handing the entire singh property over to her)
so to get the property back she brought in amrit (who is a priest) to impersonate nahar so that eh can say he did not sign any papers.
after about 10 years or so..jiji is accidently killed and saloni gets blamed for it..so in the courtroom amrit takes the heat and said tht he did it and then saloni is like no he didnt he's not even nahar and tht he is amrit and the family hears this and then they think that saloni betrayed them and thus they hate saloni.
as for sawri she rmeinds everyone of saloni...even shweta and sawri tries to keep saloni's memoris alive and bhabho sees it and thts y doesnt wwant sawri around!