I'm not sure if there is a way to do this in InDesign, but thought I'd see what people think.
From your description, the user could only go to six different pages: AA AB AC BA BB BC so we are not talking about alot of possibilities. You could have this scenario, Have an initial page where only the top row of buttons are active, and the bottom row is inactive, but visible. When the user makes a choice and clicks A, you are taken to a second page where the interface is visually the same as the first. But now the top row of buttons are inactive, and the bottom row will only take you to the possible destinations of AA AB AC. Do the same for top row B.