Challenges with Mixing Narration Types

I am currently working on a project using Adobe Captivate 12.5 and have encountered a few issues that I would appreciate your assistance in resolving:

• My project includes blocks using timeline narration (text-to-speech with captions) and blocks with attached audio (without captions).
• Mixing these two narration types has caused some issues.
• Specifically, I sometimes need to insert a gap between two captions in the timeline, but there doesn’t seem to be an option to do this.
• Is there a way to introduce spacing between captions in the timeline to improve readability and pacing?