You expand the claim of your bedroom to include this new, empty space.
Really, though, you just write your name on the wall in this new room.
You are now the proud owner of two beds, two cabinets, a chest, two doors, and a magnificent 13 square meters of floor space. Not that it matters; once you get to ShieldDawn, they'll give you your own majesty-level bedroom. You bet everyone has one, especially the valuable cheesemakers. You can't wait to get there.
>put rock blocks in backpack and leave through the empty bedroom's door.
>walk quietly down hall toward the Trade Depot.
Oh, yes! The bricks! The valuable bricks!
You can take one, put it in your backpack, and use it for all sorts of useful stuff! You can build walls, use it as a weapon, throw it, use it to hold down pressure plates-
On second thought, you'll just leave the bricks here.
Take blocks, open door, and sneak into a trading bin. (I'm assuming the migratory group is trading with the fortress?)
Oh, wait, yeah, that might work! The migrants aren't taking a caravan, but if you snuck into a bin, you could *easily* slip past!
You poke your head out the door.
Looks like the coast is clear...you make a run for it.