@Y'berg
Welfare? Uh. There are ~ 25 billion Bretonians, ~20 that are not refugees, and about 5 billion who are. Best of luck putting every 5th citizen on welfare when your industry is ruined. Even if so you want to house them close at the planet with actual infrastructure to keep it LESS expensive, as opposed to dropping them to die in desert with extreme temperatures and then attempt to ship all needed stuff to them using space transports. It just doesn't make any economic sense.
Then again you bring Earth example of a container house, with logistics already being here. I think it's possible to house them all, just on planets that already have something on them ready to accept billions of people.
On Cambridge, they could actually work to make food for themselves. The government could lease some fertile lands so refugees are more self-sufficient. Industrial people could go to Rheinland to offer themselves cheaper than local workers, causing more revolts in Rheinland.
@Traxit
Harris is the topic for another thread, but it's not even finished terraforming yet.