Ni'Var was part of the UFP before "The Burn".We do? They do?
Well, some Romulans do, since they do return to Vulcan, change it's name to Ni'Var, and that planet eventually rejoins the Federation.
Archer: The Federation. You've mentioned them before.
Daniels: Vulcans, Andorians, Ithenites, Klingons, dozens of species, including humans, all unified in a powerful alliance.
Given that Daniels is from far into the future, it doesn't surprise me that eventually. all the local neighbors join the UFP.
Everybody would get far more powerful once they are apart of the UFP.
Especially after the Dominion War and the events.