Given where you are diving, the biggest piece of advice I have is to make sure all three of you have good, high intensity dive lights. Lights enormously facilitate communication among the members of a team, and make a diver who may have gotten a little bit away from the other two MUCH easier to spot.
Teams of three work well if all three divers are committed to keeping the team together. This involves frequent (every 15 to 20 seconds) visual checks on the other team members (which can be as simple as assuring yourself that you can see their lights). When you are diving a wall structure, it's not reasonable to stay wing-on-wing all the time, because the guy on the outside doesn't get to see much. Moving into a single file formation is fine, but you have to stay even closer, and keep the lights out in front of you.
It's very doable, and as Spectrum points out, increases the resources available to the team, but it requires some discipline.