Actually were does the story is moving know we can't predict anything, first the revelation of karan secret to naina and naina finds sandhya behind it but she got backfired.
Even though Dadaji supports Naina intention, how will the story move ahead, will meghna be able to help her sister coming out of problem? Yes of course Meghna will try to figure out and naina also wont keep quite bcoz she came to know that something is wrong with karan medicine but how the sisters are going to make sandhya as wrong is a big question.
From here Naina trust in chauhan will be less and sandhya sure will make use of it and even she know about both sisters bond surely she will use something to make meghna and naina as again wrong but this time both sister should cleverly play with sandhya that too without harming family. Already karan is most affected person bcoz of sandhya.
I think from here the story will be dragged bcoz proving sandhya as wrong is not an easy task for sisters. I think Naina will find something and Meghna will find something and both the sisters discuss and will joint the clues they have come a crossed and then only sandhya will be proved wrong. I think Sandhya as Ms.Sinhania name will play as major role.
Sandhya-may be dadaji's business partner daughter, partner will be assumed as dead or he will be some how affected by dadaji and in order to take revenge of her dad, sandhya is being with chauhan.