It makes absolutely no sense to me that Dhanraj could be Govind and Rajani's elder son.
Since the very beginning of the series, Agastya hated poor people all because he felt his elder brother which is Dhanraj was cheated by a poor woman and in almost all of his conversations about Dhanraj, he addressed him as his own brother and not a cousin brother.
Other than Agastya, even Annapurna, Alka and Sonali addressed Dhanraj as Kunal and Alka's son.
Plus, it was never shown that Rajani-Govind mourned for Dhanraj's demise while it was Annapurna, Agastya and Alka who always mourned over Dhanraj's death.
Rajani-Govind always gave hints of Karan as their son, they never had even hinted of Shivani. I guess Shivani also was a later inclusion to introduce Vishwa's family.
In almost all of Agastya's flashbacks with Dhanraj, he recollected the bond they shared and how Dhanraj was always a father figure to him and it was Dhanraj-Agastya's bond which connected Agastya to Ashu.
Even in Dhanraj-Kairi's accident segment, Dhanraj kept his hand on Kairi's belly and said that his child will first connect with his younger brother Agastya. Why Dhanraj never mentioned about Karan then?
Also, there was a scene where Imastya are supposed to be preserving one pair of the same shoe which was probably given to them by Dhanraj-Kairi who are supposed to be their own siblings not cousins (the shoe ressembled a lot with the masked man killer's shoes )
Unfortunately, I do not remember the episode numbers of all these events.
Now all of a sudden Dhanraj is supposed to be Rajani and Govind's son?
This is why I said Imastya's backstory especially Dhanraj-Kairi-Ashu track is a huge mess.
I hope the CVs don't create weird tracks at this moment contradicting to what they had shown earlier!!