Same Upmaa preached how Meeshter Shah is the true and only father of her children 24/7 and never let Anuj to have a close relationship with them. She left her children in SH after marrying Anuj for sake of true father of her kids Mishter Shah. Samar wanted to leave Vanraj and be with Maa and her new family but she chose to bring Samar closer to Vanraj. She never respected Anuj as Nand Baba for her Samar and it was clear he loved Anuj a lot. He forgave Van for apparently saving ANUJ's life and then he died to save same Anuj. Vanraj abandoned his entire family for money in the end but even today she would call him father of her children.
Whereas in Prathana's case, Maa is desperate for Ansh to become Nand Baba and raise child his wife had with her abusive ex who apparently has no rights on his own child. The opposite was true for Lord Vanraj even though both Gautam and Vanraj are the same. Also Ansh is exactly like Anuj. Same situations, opposite POVs of Anupamaa. What's consistent is that Anupamaa thinks only a Shah should be a father whether he is good or bad. If Vanraj returns, she will manipulate Rahi into calling him Papa as well. She will justify this hypocrisy by saying her kids weren't as fortunate as the unborn baby to escape the clutches of their evil father and were raised by him. She will even say he raised good kids like Samar. Anything to justify Mr Shah.