An easy way to begin is to get together with your friends, 1 or 2 or the entire team that you want to have and agree to ride in the same arena. You don't have to start off riding together especially if your horse/friends horse is shy or aggressive. Instead you can all work in in the same arena and ride like you would at the collection ring of a show (if you don't show then you could each 'stake out' a part of the arena to work mainly in and ride by one another on occasion as in going down the long side or around the perimeter of the arena while the others are working in their spaces). Then when you and your horses need a break, just ride close together at walk and chat in a relaxed manner. After your down time you can all break up into your single units and work on your own again for a shorter time this time. Call another break and bring the horses together to bond and relax as you do.
Work like this a few times and the horses will begin to look forward to the break time. It will also help them when you go back to individual work as they will not get anxious about 'leaving' the group during a drill ride.
As your team progress you will be able to begin adding trot and then canter into your 'break time'. It will be easier to introduce the faster paces in pairs and then work up to larger groups.
Remember to have fun and relax so your horse will too.