I agree with what Ryszard said about the company needing to do the extensive rewrite of the documentation. Part of my day job is keeping my team's SOPs current and while it is nowhere near the complexity of a product like BiaB, it does take a great amount of effort to have and keep the documentation excellent and thorough.

However, one approach the company could consider is to analyze and re-define the most efficient and logical orderings of the current information and features with any given section meta-tagged with the alternate terms, etc. Then as has been stated, contract a documentation company to pull it all together to be distributed as a comprehensively linked PDF. I bought a library of books from an author several years ago that was actually like one big PDF and you navigated it like a web browser. Or, maybe just make the information available as a subdomain of the website.

Just my .02