Story should be themed on the FLF's fight against the Dvaered, but should focus heavily on the internal history and circumstances of the FLF. Possibly, the FLF leadership's real (but hidden) objective is something other than resisting the Dvaered.
Rough idea of a possible storyline.
Idea: Pirate alliance. In an effort to fortify their military, the frontier allows pirates free transit, maybe allows them some space on planets to farm dubious crops, or do industry that requires gravity, or is just a nice place to have holidays. Missions start with cautious introductions, through helping set up bases. Could also give some faction with pirates upon completion, maybe making them non-hostile?
Opened up by a simple test mission, should allow to get a low level of faction reliably.
The FLF can't always trust messages to standard communication methods, and so must use couriers to deliver more sensitive information. First mission isn't sensitive data, it's just a test.
Available once sufficient FLF faction has been gained (15%?).
The FLF requires secretive transport of individuals into Dvaered systems (Possibly occasionally farther afield?). Could occasionally trigger incidents and patrol pursuit after takeoff.
Available with sufficient FLF reputation (30%?)
Picked up in bars in Dvaered space, an FLF operative in trouble might request a transport back to frontier space. Triggers patrol pursuits more often.