For the NPCs, here's where I think they should go.
Abimael - Shadow Zone Wing. I don't think his shapeshifter burning grope immunity thing will be all that necessary to find Eve, and his combat capabilities and knowledge of mutants seem like a great fit for that side. Could work for either other team though.
Colonel Marie Black - U-ARM Wing. Her equipment and tactical know-how seem best suited to fight the dudes who'll be rolling in with heavy weapons. Could work for Shadow Zone, don't think she's a good fit for Retrieval Team.
Specialist Carolyn Antoinette - Shadow Zone Wing. Her laser and missile mech could work wherever, but infrared dog seems like a vital asset for finding mutants trying to sneak past the blockade. Could also be okay for Retrieval Team, if we're worried about Eve being too stealthy for us, but I feel like that sensor dog would be best used in the place where we -know- there will be issues with stealth enemies. Would be wasted against U-ARM, imo.
Sergeant Morai Lee - U-ARM Wing. This guy uses explosives. Y'know what gets fucked up real bad by explosives? Human bodies. Y'know what might not really give a fuck about explosives? Crazy mutant bodies. Could be okay on the Shadow Zone Wing anyway, though U-ARM seems the clear best fit to me. I don't think he'd be a good fit for the retrieval team at all, because explosions are kind of iffy in the "bring them back alive" department, and because I'm hoping to go for the non-violent solution there.
Captain "Daring" Derek - Retrieval Team. He can help look for Eve from the air, then move to whichever battlefield he's most needed at once she's found. However, honestly the only reason I think he should start here is just because the other two would be full already if I had my way, and he can get around the movement restriction just fine. If we do stick someone else on the Retrieval Team (ideally Carolyn, if there must be someone), then may as well have this dude start out near the fighting instead of wasting some rounds of posts with him just flying over us doing fuck all.
Basically I think the Retrieval Team can handle itself without needing heavy NPC support. I'm hoping to go with the negotiation route, and none of the NPCs seem particularly suited for diplomacy. Also, I think we'll be able to find Eve without much trouble just with the two currently on that team. Nathaniel has the mutant angle covered (meaning he can sense nearby powerful mutants) and has an achievement that raises his chances of randomly finding what he's looking for, and Roman has an infrared scope on his gun in case Eve goes stealthy. Send the NPCs where they're most needed, imo. Send them to the fights.