Robert, Great question.
I place my Brisket on first and put it on the Top Right rack and on the Bottom Right rack so that the top one drips on the bottom one.
When I put my Pork on, I put it on the Top Right rack, but toward the Left/Middle Side and then also on the Bottom Right Rack toward the Left/Middle, once again, so the ones on top can baste the ones on the bottom.
The Ribs, I put completely on the left hand side both Top and Bottom toward the back so the ones on top can drip and baste the ones on bottom. I then put the Chicken (When I cook the Chicken on the DP) on the Top and Bottom Left Racks toward the front.
I have done it this way many times, but just recently I have started cooking my competition chicken on my stand alone grill so that I can cook it at a higher temp.