You can add one additional level to your table of contents. In order to enable this setting:
- Go to Appearance > Theme Options
- On the Global Options tab, find the Two-Level TOC setting
- Select "Enable two-level table of contents (displays headings under chapter titles)"
- Click Save Changes
Now, any text in your body that has been tagged with a Heading Style 1 will display underneath the chapter title in your table of contents.