You don't need to; in order to get an empire to join the UFP, you have to already be in a federation (the Stellaris gameplay mechanic) with them. Every two years, the Federation Council will meet, during which time you can spend influence to get members of your federation to join the UFP.

Example: I formed a federation (which I named 'Federation Candidates' for clarity) with the Deltans, Saurians, Denobulans and others. One by one, I spent influence over time to bring them into the UFP.

That said, it is possible to just be able to incorporate them into your empire the old-fashioned way.

In STNC vanilla Federations are "Alliances", so look out for that.



To clarify though, the Federation Council doesn't meet every two years, it meets whenever you choose to do so in the Institutions list. Just want to be sure that people don't think it's a popup.

That said, certain actions you perform in it will put a cooldown in place which is typically two years.



Oh, and you shouldn't be able to integrate vassals as the UFP anymore.

引用自 walshicus：

In STNC vanilla Federations are "Alliances", so look out for that.



To clarify though, the Federation Council doesn't meet every two years, it meets whenever you choose to do so in the Institutions list. Just want to be sure that people don't think it's a popup.

That said, certain actions you perform in it will put a cooldown in place which is typically two years.



Oh, and you shouldn't be able to integrate vassals as the UFP anymore.

your institution mechanic is gold.