I don’t have much experience in the modeling side so I can’t really say what would be good to add in documents related to them. I do have some knowledge when it comes to project management though so maybe it will help you out.
Normally, in project management, the first thing you need to determine is the scope of the project. What is part of the project and what isn’t (working on something that isn’t part of the scope will be a complete waste of resources - time and money). To understand the scope better you usually need to talk to the main stakeholders of the project by understanding what they think the project should do. What makes the project a success or not?
Once you determine the scope, you can start to identify and list the requirements. What is absolutely necessary for the project to be considered a success? What things are optional or only “nice to have” but not critical for the success of the project (knowing what not to include is also just as important). What resources do you need to accomplish that? Do you need animators, developers, 3d-modelers, sound-engineers, story-writers, money, etc?
From there you prioritize, assign tasks, set milestones, and come up with a timeline so you can measure the progress of your project. Is your project on-schedule or behind schedule?
That’s a very general overview of project management. An asset/model breakdown sheet will probably help you figure out what has been finished and what hasn’t in a way so I think it will help.