Some points against that
1) even if Juhi claims that this is Neil's child, doesn't the guy know if he slept with his
Girlfriend. Juhi can play this card only if she intentionally drugged Neil when they were dating or if he was drunk for some reason. Neil has not been shown like that even with rhea he had intentionally done the drunk act. He was in control of the whole situation
2) I saw 2 olv - one where avni is in red saree and Juhi and she talk about finding the child. In the second olv, where all the family members are waiting for them to come, they again say something that they could not find the child and RP son was ahead of them.
From that olv whatever I could hear Neil and avni are both aware of the kid and trying to find the kid for Juhi
3) it is so against what they have shown Neil as a person that it does not make any senses and if cv do things without any sense then they will surely lose their viewers