Audit.
You get a clear picture of what the business knows and who is the only person who knows it. Every engagement opens with an audit: a structured diagnosis of where the knowledge actually lives and where decisions actually bottleneck. What is written down, what is in heads, what routes through the owner, and what would break in the owner’s absence.
The audit closes with a map: the corpus the business needs, the readers that should sit on top of it, and the order to build them in. The map belongs to the business. It stands alone, and an owner can take it and stop there.