Thanks @Turtle91.
Creating an index (which I have never done) is probably not too different from what I am already doing by creating a "Character Summary" chapter at the end of the book. But I still need to navigate away from the current page, whereas instead I was hoping to touch the entry on the ereader and see a balloon note.
Sounds like there is probably no way to achieve that.
Spoiler:
<p class="noindent"><b>Benjamin Keyes</b></p>
<p class="paraindentsmall">Trial advocate from Memphis representing Sam Cayhall for the third indictment</p>
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