In KD by the time it is Sai's birthday, Sairat have grown closer and Virat gifts Sai a ring. But in KD, Sai asks him if the ring is a birthday gift or husband to wife gift. And in KD Virat has inner monologue where he thinks its a gift for his WIFE because giving the ring is a way to make their relationship official not deal but he does not say it. He says birthday ke din diya toh bday gift hai. And Sai feels really upset in her hearr to hear that the ring wasn't more than just a birthday gift.
Additionally during birthday track in KD, pp does lot of drama, doesn't join celebration, Sai goes to call her- she pushes her away making her injure her forehead so Virat gets mad at pp for her behavior. During birthday track, Virat makes it a surprise and by then family has become just a teeny bit nicer even though they still taunt her. Infact in KD bk even serves the khaana herself! 😱😱😱
And post birthday in KD Sai brings a gift for ninad which melts him a little. They even share a hug! 😱
Yeh sab ghkpm mein itni jaldi kaise hoga?! Virat is in denial, i cant see him gifting Sai a ring already.
Maybe they are just mixing up tracks ka order a little bit but they will pick n choose scenes to show, others will be postponed. But even that may help to make the show fresh rather than blind copy paste!