Respect your point of view.
I feel that in the very first place, Pihu should've known the truth that her mother is Ishita and Shagun is her surrogate mother or someone who is like her mother but not her mother.
Abhi bataya toh nahi so, as soon as Pihu had come to know of Ishita, she should've been told the truth.
Then it should have been Pihu's decision.
Pihu has a troubled family so she is bound to be more mature than most people of her age.
Raman should tell her of the last 15 years of his life.
They should tell her of Shagun's betrayal, his marriage with Ishita, Ishita's problem, Nidhi, Pihu's birth, Ruhi's kidnap, Ishita's suicide attempt, 7 years ki judai and everything else.
They should tell her that Ishita is not her serial ki vamp and a really nice lady.
They should let her spend some time with Ishita.
Then it should be Pihu's decision.
If she had chosen Shagun, toh Ishita ka usse milna should be allowed just like Shagun is allowed to meet Ruhi and Adi.
This should've been of Shagun was positive.
Now that she's negative, I don't want her to keep Pihu cause she's poisioning that little girl's mind.