Help getting started

Hi all,I've only just started out with SimConnect so please excuse the newbie question.Basically, I want to have an external program where the user can create a flight outside of fsx. So they select their destination, type of aircraft, etc in the external program, then once that is finished, the program will fire off fsx, fly the flight, apply the parking brake, close fsx then return to the external program.The part that troubles me is the best way to create a flight plan/flight. I think that it is better to create the plan in the external program then push the plan to fsx. Is this the best way or is it best to create the plan, save it, then load it back when simconnect has initialised? Many thanks.