If this is about some kind VA/Virtual Airline thing, another possibility would be to maintain an online flightplan database and use FlightGear's http bindings to fetch flight plans - analogous to how scenery/aircraft and navdata can be downloaded on demand. Obviously, that would require a little server-side script (e.g. php/python) - but otherwise, it'd be fairly straightforward to come up with a web service for managing VA flight plans in a central fashion. As a matter of fact, it would even be possible to host up-to-date navaid information that way, while ensuring that all VA pilots are using the same navdata.
I once documented the underlying idea in the wiki, which includes sample python snippets to implement the server-side to fetch data and load it into FlightGear:
http://wiki.flightgear.org/Howto:Making ... from_NasalThese days, there are much better methods available - but the general idea is the same, and would be fairly simple to prototype, and even to extend to provide a holistic navigation data web service, which could include all sorts of VA stuff - it's a recurring idea actually:
http://wiki.flightgear.org/A_NavDB_Web_ServiceAnd it is also something that could be implemented on top of Richard's Emesary framework:
http://wiki.flightgear.org/Emesary