Thanks for your replies! I don’t want to complain about an extra colony, but I try to imagine it from an in-game perspective:
Wesley: Professor Brindley?
Brindley: Yes, Wosley?
Wesley: Wesley, Sir. I pointed my new telescope to the gravitational anomaly in the Iconis system. I have analyzed the gravitational and electromagnetic data, and, Professor, it turns out to be a previously unknown planet! Furthermore, …
Brindley: Nonsense, Wodley! How could we have overlooked a entire planet in the age of intergalactic space travel?
Wesley: I also analyzed the spectral data, Professor Brindley. It appears that the new planet is inhabited. My first analysis suggests about 3 billion people.
Brindley: Oh these incompetent PhD students these days. You wouldn’t have gotten away with such nonsense in my days, Wasley. Put the adaptive optics to maximum and let me have a look...
Wesley: Yes, professor. It's Wesley, by the way.
Brindley [looking through telescope]: Fascinating! It’s full of people! Get me my notes Worsley and cancel all my appointments!
Hours later an emergency meeting of the government takes place:
Science minister: I have just received a report from Professor Brindley on Tauris Prime. He affirms me that he has finally solved the problem of the gravitational anomaly in our home system. It turns out to be a planet inhabited by three billion of our people.
Minister of Defense: That is ridiculous! Are you suggesting my scout ships have been flying past that planet for decades?
Science minister: Not only suggesting, but also saying.
Minister of Defense: But your survey ships did not detect it either, despite their incredible administrative upkeep! I say we nuke that planet to dust, to get rid of this embarrassment. We would be the laughing stock of the galaxy!
Prime minister: Gentlemen!
Minister of Culture: I say we welcome our brothers as new members of our glorious republic. Just act as if the discovery of a colony of three billion people in our home system were the most natural thing.
Minister of Treasury: Don’t forget to send the tax declaration forms with their new republic ID card. I estimate 500 billion credits in back taxes for the last hundred years.
Prime minister: Agreed! Also order them to sponsor our shipyard. Now, let’s have lunch!