Maybe there can be some of the advantages of a system sent along. A multigenerational fleet with multiple ships, capable of trading among them, but also providi

Maybe there can be some of the advantages of a system sent along. A multigenerational fleet with multiple ships, capable of trading among them, but also providing a degree of separation and differentiation. You could even try attaching some engines to asteroids and comets full of useful materials to send along side the fleet, ready to be used if the self sufficient systems fail, and for the colony when they finally arrive.