I really don't understand Omi and Sonali's hatred towards Sai? I mean did I miss something in the show? Did Sai do something to them? At best I know Sonali was grateful when Sai fed Mohit when they were too helpless to take action as parents? By why this level of deep hate towards her? What has this 19-year-old done to them?
As for Bhavani's sudden change of heart, it's just a wee bit too much to digest. The only thing I can think of is that this is her own selfish reason. She loves Virat and Samrat (as shown in the initial episodes) and I think Devi's words have had a deep impact on her indicating that there will be no Virat without Sai and vice versa. So probably the fear of losing Virat has impacted her. Otherwise, I don't see any other logical reason for her to have any compassion for Sai at all.