Nice mod, really cool sprites: a cohesive theme while keeping the skeleton of the base ships intact.
Some bugs:
1. the II invictus's built-in gun is set to a turret not a hardpoint, so it can turn (really slowly). I suspect that it's supposed to be fixed facing forward?
2. After cheating in the blueprint, I cannot get the player faction patrol fleets to use these ships. I select the ships in the fleet doctrine screen and for some reason, my fleets just won't use them. Is this intentional or some wierd bug? The only time I've seen patrol fleets ignore selected ships is when they're automated, maybe you've added a wierd tag to the II ships?
Also regarding a faction, it may be possible to add a sort of easter egg, hidden market belonging to the II battlegroup similar to what Sephira enclave or Anakaris reperations society does with it's eponymous faction where the faction market is set to hidden so it doesn't show on the map like the randomly generated pirate/luddic stations. Could be added to the edge of the map as a hostile "boss" starsystem, with a custom fleet hanging around a starbase. Having to fight the final remenants of the II would be a good way to earn the blueprint I think.
IMO I don't think there's anyway to have a II fleet belonging to the independants that would not have been siezed by the hegemony. Remember they claim to be the true succesors to the Domain so there's no way they would let anyone else have ships belonging to another battlegroup. But then it's not like modded factions have ever fitted in lore so do whatever you think is most fun/interesting.
Also a question, do you plan on adding faction specific weapons like the IX battlegroup mod does or will you stick to ships/wings?
Anyway, cool mod especially for your first. Excited to see where it goes!