1. Dev needs to go against his mother, even if it is for the very first time. He has no choice. All doors are more or less closed.
2. Dev has to get on his knees and make that "worlds best proposal" to Sona. It really does not matter when or where. He just has to do it.
3. He needs to tells sona that he is willing to marry her against his mother's wishes as she is equally important, if not more, to him. In fact for his own sanity, she is more important now than Ishwari. He just has to do it.
4. Sona should refuse to marry him because she needs to do it the right way. However, she needs to tell Dev that all she wants is for his support. She needs to remind Dev that both of them are in this together and he is not alone and he has nothing to fear. She just wants him at her side.
5. Dev must give a committent to Sona that even if Ishwari takes a gun and shoots herself, he is not going to move from Sona's side ( basically no emotional blackmail)
6. Dev and Sona then go to Ishwari and tell her that both love each other very deeply and are meant to be with each other. They must also tell her that they respect her and worship her for all her past sacrifices and how she held the home together. They need to confront her as mature adults and not as runaway kids. There is just no choice.
7. The scene of the promo must play out where Dev and Sona ( he in the grey suit and she in that yellow dress) stand before Ishwari together.. as ONE. Ishwari must confront her own fears of having to share Dev with sona.. the mirror promo is what i am talking about.
8. Then starts the next phase of KRPKAB to regain its lost glory. Dev and Sona fix things with strength, courage, wisdom.. being together always... even if they are not married due to Ishwari's insecurities...
9. Dev and Sona address Ishwari's insecurities and finally Ishwari realises that all her insecurities were absolutely unfounded with a girl like Sona and calls for a grand wedding.
10. Curtains down. All live happily ever after.
Giiven what has been created and what has come to pass, i am not able to figure out any other path of redemption in my finite brain.