STEP 3 - For each object, send it to its formation position (relative to group's position).
What about making the group moves as one object in the open area , and every object will move on its own when facing an obstacle ?
The way your objects move reminded me of the old typewriter , the objects move few stpes up and right and then return the straight line of the path and so on ,
Here is a video where the wole group moves / rotates as a singel object (like a rectangular object )
Hope this helps .