When stopping as a group at an intersection, break stagger formation and pull up beside the bike in the same lane. This will reduce the length of the group by half.  Stay in this formation until you are through the intersection.  Because the group is half as long it will take half the time to clear the intersection and increase the odds of  keeping the group intact.

If you don't make it through the intersection with the group, don't worry.  Don't take a chance and run a red light.  The leader will know that you are not with the group and will slow down, or wait for you down the road.