single editable document multiple indexes

[Dingo]

Looking for advice
I wish to create a single editable document approx. 4-500 pages


From this document I wish to produce multiple documents, from the single editable document. Each Document comprising of parts of the original editable document
Now my problem is that I have no idea what to call this so that I can google it

The Document I’m referring to is a business operational manual, so the editable document is constantly changing with policies and procedures, and multiple Documents will be for different departments (most will share similar pages, but all will be different)
So I’m trying to find a way I can a create a header, index and link to each page. With the hope that this Document can be printed out in PDF with out update each sub document each time.

Is this something that I can create in Word and export to a PDF convertor?

All feedback welcome