I think I am gonna pass on the twins idea for this game...it seems like it would work a lot better tabletop, since it would require a lot of coordination.
For background connections, I like the idea of them being a recent, but tested group...sure, they knew of one another in the Shadows before the Red-Eyed Johnson screwed them all, and some of them might have had personal connections, but the Screw, and the John Smith Job, united them, and they've done a bit since then. This lets them all know and trust each other, but still leaves room for some secrets...and lies. Which gives us a chance to grow the characters in play, get to know them by our characters getting to know each other. Maybe they figure this Phoenix Protocol might be a long-term thing, and start settling in as a team.