Whether we agree or not, the fact is if the truth is revealed at this stage will be the kids. Ved is already feeling scared of losing his father's love and company the moment he heard about Vansh's father planning to send him with his mother away from him. So he fears what if his own father also does that and in that fears he is already clinging to Suraj. He is under the impression that he is the universe of Suraj and suddenly if he comes to know that there is one more person to share his love and that too, he is his rival (as he thinks right now) Vansh? Added to that he was under the impression that his father never lies and was shocked with Mohit's truth and now if he realizes his father and even his mother who is an IPS officer and advocate that not to hide anything and never to lie have lied to him for the last 6 years and they have given away their child to someone else and never bothered to be in touch with that child. They will also instill fear in his mind that there may come a day when his parents might abandon him also like Vansh. Added to that he will go scot free lying as he knows that everyone in his family lies and have been lying for the last 6 years and who knows what else is hidden form him or what is actually the truth.
On the other side, Vansh who is puzzled at his father's behavior and is clueless about the reason for his movement to Jaipur from Ajmeir. He thinks his father is the best father who loves him a lot and do anything fro him. He has so much blind belief in his father that he has not even asked his father why he cancelled his birthday party or why he should not go to school? For such a kid, if he comes to know that he is not their son and he was son of Ved's parents, how will it affects? He will be shattered. One things his parents didn't wanted him and so they easily handed him over to someone else and didn't bother to meet him even once. he will hate Surya and will not be happy and call them Papa & mamma. On the other side, he will also feel sad that he is not AA's son and whatever the love they showed him was not genuine but they tried to love him only for the happiness of their daughter and will drift away from them. And his loving sister Bulbul will become a villain (vamp) in his eyes because, she was the cause for his status.
Even though we are angry at Ankur for acting so impersonal and insecure, his doubts are also not baseless. Vansh and Ved are not at the right age to understand what happened 6 years back and why it happened. So it will be better for Rathi's move slow and make arrangements to just meet him up as relatives and not as his own family. If they take drastic steps to bring Vansh back to RM as Surya's son, the chances of both kids get in to trauma are more.
Not only that, even other kids will be shattered thinking what all might have been lied to thema nd they will not be able to trust the elders hereafter.