Precap se toh yehi lag raha hain ki ManAv ki nehi, SunDar ki fight milne wali hain humein. That was definitely unexpected, maza ayega zarur.
Here's how I think the divorce papers will be burnt down to ashes:
I am considering that Raghav firing the shot is actually Pallavi's imagination and the precap wasn't sequentially showed (as always!). So when Mandar turned to take Pallavi's sign on the papers, she was picking up the thali full of diyas. Then due to Sunny's accidental push, the papers will fall on the diya thali and since there are soooo many diyas on it, the paper will be irredeemable.
Then the epic SunDar fight will happenš„³Sunny's ego will be hurt after Mandar hits him. So to take revenge for his beizzati, he should join RaghVi's team to take down Mandar. Kaha hum Sunny ko spiritually Deshmukh samajh rahe the par banda toh Pallavi ka true brother nikla. Humesha madat karta hain apni behen aur jiju ko.
On a side note, hope Raghav gets an earful from Pallavi for coming up with such a stupid idea of sacrificing himself.