Hi Gan,
It is good to see you after a long time.
You are asking the wrong question Gan.
Surrogacy was only for Shagun.
They could not make Raman cheat on his wife with his ex-wife for another child like any other show so they came up with this unique idea of Shagun and Raman third child with Ishita eggs to be used without her consent so that Shagun can deliver Raman third child and be the central figure in Raman life.
Once the surrogacy started if you remember they showed Raman catering to Shagun whims and becoming mesmerized with her beauty but TRP took a big dip lowest if I remember correctly 2.4 and they hid Shagun and brought in the Ghost track which brought them their highest trp of 4.2 which revolved around the IshRa then bam came Shagun again with the Ghost track changed into a plan track which was very obvious in which Ishita was made to act like a fool.
Then came the delivery time if IshRa are together then how will the baby stay with Shagun bam came the leap and IshRa were separated Raman was brutally murdered that day till today after that episode I cannot see IshRa I can only see Divan acting. Shagun stayed with Raman and baby.
Ishita came back then how will Shagun have Raman and baby viola we have custody where in Raman doesn't honor his dead wife but put his ex-adulteress wife name as the mother of the kid and wipes out the memory of the real mother from the kids existence so Shagun manipulates the kid saying that the real mother broke her home and the kids leaves the house which is soon going to be followed by Raman if spoilers are to be believed
Once again Shagun in the lime light with Pihu and Raman with her so the purpose of the surrogacy is achieved.