You can set the topic for a response in a Response List file, or in AIML, and import it into your bot.
Just set the topic for each response in the topic.
Bot Libre also supports isolated conversation trees using the "next" property.
For setting the topic in code, you would set the Primitive.TOPIC relationship on the question's Primitive.RESPONSE relationship meta.
For example responses lists, AIML, and other scripts see,