I was just seeing the episode where Sundari is telling
Rudr the story of his father.In that she mentions that when she came to know that she was pregnant at that same time kavita also told of her pregnancy to virendra.
And when she went to ask virendra for her childs rights he said it was illegitemate so she was angry.
I think she might been so angry as to take revenge from virendra she might have switched the boys at birth or so. So ant is sundari+virendra's son AND rudr is kavita+virendra"s son.
Hence the sudden interest in Antariksh