Jay was a puppet from the beginning I don't think anything got changed in the case of VaNi maybe the twin track wasn't there from the beginning but articles about Sharad character shown negative at first and will turn positive later has always been there. Some even said Mohit is a second lead, It was always Naagin and Cheel love story.
Veer and Bani scenes was always presented better and more grand and Sharad and Surbhi both emote their part beautifully even with poor screenplay their chemistry is sizzling and they still bring the intensity out perfectly. Jay character is just a prop, and he indirectly always brings VaNi closer like last week when he mentioned to veer about Bani being in danger and also it was Jay phone that lead Bani to Veer.