you know, I have a thought.
Most stories of the Taurians fleeing have them running into the deep periphery.
What if they fled in the opposite direction? Inward, not outward?
The thing is, the Taurians had a robust space capability, and the Inner Sphere has thousands of worlds, even more systems with no habitable planets, and with Btech sensors, a space station or ship that hangs around the outer orbits is, well, pretty much invisible.
And in the pre-HPG era, keeping track of ships can be a pain, especially if you have money to had to organized crime, and a nation state, even one on the cusp of losing a war has a lot of money to hand criminals. (mind you, they're not calling themselves the Taurians--nope, they're just another band wanting to launder loot from the war, and there are a lot of perfectly "honest" mercs and officials with the SLDF doing exactly that*).
So, now they have some "legitimate" jump and drop ships, and they keep their hidden stations and jumpships, but they don't seek out new worlds. Nope, they find worlds that won't ask too many questions about new immigrants who have money and want to carve out a new home (likely some of the less fortunate worlds in the Lyran commonwealth, but honestly, a world, outside of somne of the most heavily populated, is a big place). And to be honest, just look at the RW for how many cities, states and even nations who are rather uninterested in inquiring too deeply about the nature of a company that pays its taxes on time and employees locals.
And as the years pass, these hidden exiles found their new companies, always very law abiding, even if they're just a little less productive than they should, while the hidden stations that fled the concordat serve as collection points, maybe even building the first shipyards needed to build the liberation fleet. And when the occupation ends, the Protector will be presented with his new military, a hidden army that has learned the lessons of the last war...
*The SLDF was nuking cities by the end of the conflict, and had explicitly said: the rules of war? What are they? I expect a lot of officers and men saw looting as a good way to secure their retirement.
Okay, this plays off of a couple of ideas:
if you want to try to restore the concordat, running into the deep periphery isn't useful--by the time you get established the Star League will be utterly invincible, since nobody knows about the worst Christmas Day ever.
But the Inner Sphere is huge and before HPG's lots of planets aren't fully on the grid, and people hardly ever ask about investment opportunities, which is how the mafia can get its claws into towns.
Unlike the deep periphery, where an industrialized world is really painfully obvious, if you set up say, "widget factory and covert town for Taurian expatriates" it tends to get lost in the noise, because well, duh, it's a factory, there's a billion people on the planet, why are you surprised. Even if someone finds out that it's up to no good, well, what are they more likely to think? Organized crime, or secret Taurian plot to restore the might of the Concordat?
Given the Taurian's generally high education, and with some palm greasing, local governments might not even worry about immigrants. They pay their taxes and if you're say, in the Lyran Commonwealth, you're not going to go back and try to retake Taurus, that's just crazy. The SLDF is happy to have refugees elsewhere, both due to humanitarian concerns and its one less bunch of rebels--besides, we have to keep looking for those rumored escape fleets heading to the Taurian world of FREEDOM!
Instead of having to start from scratch, your hidden organization can take advantage of well, the Star League. IE, instead of having to build your toilet paper factory on the world of FREEDOM! you simply go down to the local corner store. More specifically, instead of being dependent on what ever engineers you brought, you can take advantage of all the non-secret work being done, send your kids to official universities, and hey, maybe, if you're feeling lucky, see if you can enlist some people into the SLDF.
Now, I'm not certain where this would go--one amusing thought is that they're gathering their forces to battle against the SLDF for the New Vandenberg revolt and then Amaris backstabs everyone and the secret army finds itself working with Kerensky.
But a big part of this is that a lot of times Btech seems to ignore just how huge the setting is. It'd be pretty damned easy to get lost and disguise yourself, especially if everyone is assuming that any Taurian holdouts are heading for the deep periphery (and you could assume that Taurus had some "secret" files for such opeations that wouldn't be destroyed before the SLDF got them. Odd, that.).
also, why should Comstar be the only people who can keep up with these decades long conspiracies and hidden facilities?