Rhea unfortunately despite being the real sister of prachi will be her worst enemy in her life for many times to comes, whereas mooh-bholi behen shahana would be more of a sister to prachi.
I don't know why, I am afraid they will do to Shahana what they did to Purvi and Bulbul. The former was implicated of some crime by Aliya successfully and sent away from her home while Bulbul was killed. Both had been Pragya's strengths. I am so stoked that in future, CVs will take the same route with Shahana