I said in another thread that if I was awesome at scripting (and I might still learn it) I'd add a mod which grants access to ATF ships though a plotline that starts on Earth, and is basically like this. The idea being that when you land on Earth, you're contacted by TCI (Terran Central Intelligence) and offered a special position within their organization. Officially, you're honorably discharged from the Terran military, and all further work for them is purely on a contracted mercenary basis.I also like this part... You could make plot-based missions that require you to make certain level contacts with different organizations, like the NMMC... Also there could be a parallel plot-entwined sequence missions, given to you by a wing of the ATF, of course, that requires you to blend and go 'undercover' in various pirate (and other) organizations that provide a certain threat to Terran space... In general I like, and so promote, the basic idea of a middleman co-op/undercover agent....
And as I said you probably don't need to tweak the start file, you'll probably delete all other starts (not that I have any doubts about you, seriously)... All you need is a mod that adds this start to the menu... A script can't add that kind of complicated stuff... I think...
Unofficially, TCI orders you to build up assets in the Commonwealth, with missions that give you things like, 'buy these kinds of stations and deploy them in Commonwealth territories' or 'build up your rep with these people to this level' as well as missions that require you to purchase or otherwise 'acquire' certain models of ships like a Split M2 or Paranid M8s or an Argon special weapons factory. The idea being that as you build up your trust with the TCI and your reputation with the Commonwealth, they grant you access to better ships. Since the TCI and the ATF would have access to the same class of ships. That way, since the requirements would be either that you can buy or capture pretty much any ship in the galaxy anyway, the highly advanced Terran ships wouldn't really be unbalancing, because it really would be end-game content. I mean, by the time you can buy or capture any M2 in the whole galaxy at will, I think you've earned the right for the big Terran monsters.
Then the mission string would run the gauntlet between working for the Argon, Boron, Split, Teladi and Paranid, while constantly reporting back to TCI, who may just tell you to keep them informed, or may change your mission objectives slightly. And peroidically the TCI would also give you missions of their own, which would usually be how you earned new ships. Like, "We don't have much tactical data regarding the uncharted gates in this region of space. Please scout them for anything unusual. To assist in that, we're going to grant you access to the Valerye class scoutship." or, "Our information suggests that the Terriformers may be massing a strikeforce near Paranid space. However they haven't attacked the Paranid directly, and the Paranid refuse to commit ships for a strike unless directly provoked. We're granting you access to our M7 frigates. Use them to lead a strike into this Terriformer sector and destroy these three stations. That should provoke the Terriformers there to counter-attack against the nearby Paranid sectors, and the rest should take care of itself."