And just before dieing Jiji tells Saloni that Sawri is her real daughter, so only Saloni, Saloni's parents and Sawri know that she is the real daughter, They don;t tell the entire family becuase Shweta is a heart patient and she won't be able to face the truth.
Nahar died long time ago, he was basically killed by Jiji, but Saloni then found a look alike of Nahar and took him home with her, becuase the family needed the support of someone at that time so she couldn't tell them that Nahar has died. Nahar's look alike stayed in the singh house for 11 years and pretended in front of the family that he was Nahar.
While Saloni's case is going on in the court the family fins out that Nahar has died and the person who stayed at their house for 11 years was infact Nahar's look alike. The entire family starts hating Sali for this reason and they also kick out Nahar's look alike out of the house.
And they hate Sawri becuase she resembles Saloni in many ways. she is a maid's daughter and Sawri also keeps reminding them about Saloni. But the family doesn't want to hear Saloni's name in the house, so they dislike Sawri.
Hope this helped, you can ask for any clarifications if needed