How can I let my assistant use a part of the knowledge only in a certain situation?

This is pretty much a beginner question I guess: I want to set up an assistant for my website. My company has two offerings, that have only little to do with each other. How can I set up the assistant that it will give information only about the first offerings, and about the second only when it is specifically asked after that

My guess is that I could solve that with different Topics?