How deep should an organization go

Answer:
Two topics: documentation and level.
Documentation – ISO 9001:2015 has no mandatory requirements about documenting who are the relevant interested parties and what are their relevant needs and expectations.
Level – There is no explicit guidance on ISO 9001:2015 about this. What is the scope of your organization’s quality management system? Perhaps the corporate level has a scope much wider than the scope of your business unit. Also, normally, the corporate level don’t handle customers every day, it is not at the corporate level that products and services are manufactured or provided. The corporate level is best to handle, and generate value, through managing a set of business units.

The following material will provide you information about interested parties:
- ISO 9001 – How to determine interested parties and their requirements according to ISO 9001:2015 - https://advisera.com/9001academy/blog/2015/11/10/how-to-determine-interested-parties-and-their-requirements-according-to-iso-90012015/
- free online training ISO 9001:2015 Foundations Course - https://advisera.com/training/iso-9001-foundations-course/
- book - Discover ISO 9001:2015 Through Practical Examples - https://advisera.com/books/discover-iso-9001-2015-through-practical-examples/