This paper presents a software component, the plan database, which provides the needed services to define plans, execute them and more importantly adapt them during execution. This plan database handles fully dynamic plans (insertion and removal of tasks), defines task transformation operators and provides tools for safe concurrent execution and modification of plans. These features are essential in multi-robot and human-robot contexts, where tasks need to be easily passed between systems and plan adaptation helps coping with the unpredictability inherent to systems where multiple agent make decisions.