Let's set the record straight.
The UEF and the Talus Empire have no relations that would prompt mass migrations on the part of the Humans. In fact, the UEF and the Talus Empire are in two different universes, and the link between them, connecting the UEF capital world of Earth (not the one that's been destroyed - the UEF's Earth, which is very much intact) and the Alliance core world of Blacken Prime, is monopolized by the UEF Military Service and is open only to active military personnel, and in rare cases, their families.
The UEF's population sits around 190 to 200 billion. Earth is occupied by about 9 billion people. The UEF owns sixteen Prime Worlds with an average of 3 billion people per planet, for a total of about 50 billion people (accounting for rounding error). The UEF owns approximately 110 less important colonies with an average population of 1 billion each, for a total of about 120 billion. The UEF also owns about five hundred satellite colonies with small settlements typically less than 25 million in size; these account for a further 12 to 15 billion.
The Alliance's human population within easy reach of Blacken is somewhere around 3 million at most. Less than a million humans live on Blacken, with sparse colonies on the other Alliance-owned worlds. The UEF is claiming worlds in the Blacken universe for military purposes only and has no immediate plans to settle them.
We retconned any fleets in the millions out of existence in the rollback. The UEF's manufacturing capabilities, though formidable, can't turn out millions of ships each with crews of a million or more. The Colossus-class carriers are rarities - most ships will be staffed by less than a thousand, with automatons to fill in the gaps. A million people will not fit on a ship one kilometer or even five kilometers long, the size of a typical UEF battlecruiser.
In conclusion, as long as we are aware of all the numbers at play, everything should be reasonable.
Also, since there are no longer hundreds of millions of humans to move in response to the Talus Incident, that section of the post should be edited.
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