SR22Pilot

Hello Is there any way for a pilot to submit a flight without the flight being in the schedule system? For example, I have an acars that allows for the pilot to fly from any departure airport and arrival airport of there choice using aircraft only in the fleet. Once flown, They can end the flight and the details be sent to phpVMS to be processed and added into the database. Can this be done without getting an error saying the flight number does not exist in the schedule?