I may be wrong here Jim, but I believe that your best bet would be to use
styles. Mark the Chapters as Heading 1, then demote any other headings to
be used int he TOC by one level.
If your TOC has been set up to pick up styles or levels, then all you should
need to do is add the chapter to the document, and then update the TOC
field.
If the TOC uses table of contents entry fields - that is, the Chapters are
marked using TC fields - you'll have to add a TC field for the new chapter.
If you are unfamiliar with TOCs, you might find this helpful: