Document assembly

I often need to create about 30 large documents that contain sections of generic text, as well as client-specific paragraphs and tables, Even though the generic text gets checked and signed off before I create the multiple client-specific documents, the reality is that my stakeholders always make last-minute changes to the generic text, so I then have to make those generic changes 30 times. I'm looking for a way to: 1. create a master document for the generic text 2. create multiple documents that contain the client-specific fields, paragraphs, tables and possibly graphics 3. merge the generic text with the client-specific information. 4. MOST IMPORTANTLY make changes to the master document that automatically go through to all documents, Is there is a way to do this in Word? Does the necessary software already exist? Can you develop something that allows me to do this based on MS Word? Please ignore the budget below. My budget depends on whether you teach me about an existing method or develop something new. Thank you