After creating a Table of Contents using the automated tool, how to manually add further lines to it

[Swarup]

I have written a 300 page MS word file consisting of a series of transcribed lectures. Of the 40 lectures, only 32 had recordings which I could access. I could not locate recordings for the remaining eight lectures. As a result, for these eight lectures there is no transcription i.e. no chapter in the book. Nonetheless I wish to include them in the table of contents (TOC) to show readers where those lectures would have been located in the TOC and what their titles are. For each of these eight, instead of a page number, I wish to insert "sound file unavailable". I've created a TOC using the automated tool in MS Word 2016. After having created that TOC, is there a way for me to add these eight lines in their respective locations in the TOC?

Or would I have to discard the automated tool and opt for making the TOC manually? This sounds difficult and thus I would far prefer to use the automated tool if possible. But if there is no option except to manually create the TOC, would I then have the option there to add these eight lines in their respective locations?