It's good to add addtopic "new topic" when dialogue is supposed to add a new topic. Sometimes new topics aren't hyperlinked when another mod's topic includes the same words, so they don't get added.

Example if a sentence should link this topic "I would have you deliver a message to Khuul."
but another mod could be adding the topic deliver a message. Even if the npc who speaks the first line would never have dialogue for "deliver a message", the engine checks if it's available and that can be enough not to link the intended topic (priority may be longer topics)