Best practice for creating and managing large requirements documents


I am wanting to record large requirements documents that are interrelated. Essentially a web of connected standards and specifications. Is it best to first add all these standards and specifications as individual requirements then create a requirements document that references the requirements or to create the document from the start and create the requirements directly in the document?

Additionally, is there a way to add a high-level requirement into a requirement document and be able to expand that requirement to input all the outgoing linked requirements and their outgoing linked requirements and so forth?