Mrunal Thakur and Priyanshu Painyuli will play siblings of Ishaan Khatter in RSVP and Roy Kapur Films’ Pippa. Soni Razdan will essay the role of their mother. The film is being directed by Raja Krishna Menon and is based on the book The Burning Chaffees, written by war veteran Brigadier Balram Singh Mehta, a veteran of the 45th Cavalry Tank Squadron who fought on the Eastern front during the Indo-Pakistan war of 1971. Ishaan plays Brigadier Mehta in the film being produced by Ronnie Screwvala and Siddharth Roy Kapur. The film will release late next year.