Have you cooked for this many people at once before?
@sonofabutcher is spot on with how I would set up the grills, but if it's just you, it's easy to get frazzled once you start having to time pulling off the meat to rest and then the various sears while managing new coals and meat temps. I've only cooked for this many people at once three times, and any advance planning you can do - do it. Set up a comfortable work space with tongs, probes, timers, foil, platters, garlic butter, etc. - whatever you think you'll need when you start because once you start pulling, resting and searing the meat, things move very quickly. I also found it helpful to sort the meats on the kettles by doneness requests - in my case, most of my requests were medium rare, so I could rest/sear those while the mediums were still coming up to temp. Don't focus on being perfect - your goal is getting the meats into a reasonable temp range. Lastly: have fun and know it's gonna be controlled chaos for a bit! Have someone take pictures of everything! Good luck!