I was hoping for a Federation Splinter Faction, but I'll settle for this Featured Episodes Series until then.
You already have that, it is just called the Federation for short. The Feds in this game are so far from the ideals of the Federation it is laughable. Cloaking ships, illegal weapons, the list goes on. The Rihannsu have no such cognitive dissonance in their operational modalities.
I just think of the Feds in this game as the Mirror Universe Feds, an Empire. Just much less competent.