From any kind of 2x4: Identify whether you are a leader or a trailer (in your
box of 4). Then, working to concentric box spots, if you were a leader do a
Partner Tag and then trade, and if you were a trailer do a trade and then Partner
Tag. These actions are always done concentrically, no matter how awkward that
might be. The "lines to lines" rule does not apply, however. Work to spots.