Can we file a FIR later

My question is that my friends family was travelling to UP and on their way their bus fell into a big pot hole on the road and all of them suffered injuries. One of the victims was injured badly and was taken to the hospital and unfortunately he passed away. Amidst all of this the family forgot to file a FIR with the state police where the accident took place as there was no other party involved in the accident, now the insurance companies require the FIR and also to get the post mortem report we need the FIR copy. The policy has a time limit of 30 days within which claim form along with documents have to be submitted and we know that is too less to get an FIr done in other state. Can you please guide us on 2 things: 1) How to get FIR in back date or present date mentioning the accident date. (The accident happened in Roorkee and we got the patient to AIIMS Delhi where he breathed his last.) 2) Any way we can ask the insurance company to give us extension as the process will take sometime.