It could be possible that Bani's real mom gave Bani up to Nikshikant Dixit and his 2nd wife (pia and rano's mom), when Bani was a baby.. and Bani's real mom moved to Mumbai. 7 years ago when Jai and Roshni were driving thru park road, they had an accident and crashed into her.. and she died, or is in a coma.
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who knows yaar
anything is possible...
maybe 7 years back Nishikant came to Jai for money to save Kiran while she was sick or dying or something (since we dont know when exactly Kiran died) and Jai refused because of Nishikants debt problems or something...and Bani's mum died...
anything is possible
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The above theories are more plausible to the cause of Jai's and Roshni's fear.
1) Bani could have been adopted and her real mum could have been seriously injured during the accident and knowing that it was Jai's car that hit her, she must have told Nishikant about it and during the investigations and trial it was somehow made to look that due to lack of evidence both Jai and Roshni was acquitted.
Nishikant has been blackmailing Jai & Roshni ever since then. Jai was afraid to face the same judge for his divorce for fear of Bani finding out about the Park Road incident cos once it was revealed Bani somehow will be able to recall some of the things that Jai, Roshni and her father has kept a secret from her all this while.