Rishita was briefly disliked by Suman because she disrupted the marriage that was supposed to patch Suman and Mama's family. At that time she felt for Raavi and according to her what Rishita did was great injustice , but she did not hold Dev accountable (Suman is always that way, never holds her sons accountable) But when Rishita saved them all at Khandar, her value started going up in Suman's eyes. Since then Rishita's stock has been on the rise.
She saved them from Khandar
She saved Shiva from Jeera kaand
She saved Dhara and Suman from those gypsies who hypnotized and tried to loot them both.
She is also credited for getting the brothers out of jail during loan kaand as she talked to Janu.
She helped Shiva to get released from jail during IVF kaand.
From Suman's POV Rishita has done more for the family and Shiva than Raavi.
Hence she is treated like a queen bee, Dhara was right when she said "sar pe bitake rakha hai tujhe"😕
But most of these kaands are done by her family only.. In my opinion more than Rishita saving them, it's about if she doesn't Janardan family will ruin them.. Suman is a big fattu, She knows Rishita is capable of ruining them, so it's better to keep her on their side