If you work on the project that leverages the existing functionality how do you document the existing requirements pertaining to your project because they are part of the overall workflow? For example, you develop requirements for a new screen of the existing process. How much of the existing requirements you need to specify in your BRD so it will be helpful for testers to read a full story and see all workflows to write accurate and complete test cases. This question applies to a waterfall environment.

Thank you.