The overall project plan support, and are, supported by the Instructional Design [ID] documents as they are constructed in much the same way. Similar to a couple riding a bicycle built for two the overall project plan balances with the ID design document as both work in tandem moving the project forward.
While the design document is composed of learning objectives, key points of content and concepts along with processes and activities. The project plan works with the design document via the initiating and planning stages [creating project charter & identifying stakeholders].
Both ‘riders’ of the tandem bicycle might take turns riding in the front or back of the bicycle or even propelling the bicycle solo, for short periods of time. Yet, a bicycle built for two arrives at its destination [the specified project stages of completion], fastest and in best form, when both riders are working in unison.
The instructional design process is similar to the project management process in that both spend a vast portion of their life span in the analysis and planning stages. Just as one may ‘plan and plot’ the path for a long bike ride, adjustments to the bike, changes in weather, and even detours can cause riders to change course and make adjustments yet the bicycle [and riders] do arrive.
The similarities are that it is all about the journey, not the destination. Both the Instructional Designer and Project Manager are headed to the same destination-project completion.