The final scene of The Dark Knight is also a great example. We have a triangle of Harvey Dent, Jim Gordon and Batman, and Gordon's family in a fourth corner, but we never see two of them in the same frame.
When Dent walks to Gordon's wife and puts the gun to her head, the Dent-Gordon line crosses the stationary camera, so Gordon turns to the right of the frame when he talks to Dent. Then Dent takes his son, moves the line again, and then Gordon talks to the left of the frame.
Then Batman appears, but without an establishing shot of all three of the characters, we still know where he is in relation to all the others, because of the line.