There's two methods for using the Pathfinding behavior.
The first method involves timing the objects with the behavior to go one after the other to end up at different positions that you must choose.
The second involves the same method, but with only one object finding a path, and the "swarm" using that path. Its much more complicated in that those objects will use their own formulae to detect each other as well as bottlenecks, collisions, etc.
The latter is extremely complicated, and entire books have been written on the subject.
Don't use physics, don't use solid, do read a book.