The issue of multi-agent planning in highly dynamic environments is a major impediment to conventional planning solutions. Plan repair and replanning solutions alike have difficulty adapting to frequently changing environment states. To adequately handle such situations, this paper instead focuses on preserving individual agent plans through multi-agent coordination techniques. We detail a reactive agent system architecture in which the main focus of an agent is to be able to achieve its subgoals without interfering with any other agent. The system is a 3-level architecture, where each level is guided by the following fundamental principles, respectively: when is it valid to generate a plan for a subgoal, who is most appropriate for completing the subgoal, and how should the plan be carried out.