So FE8, unlike FE7, actually stores data for forcing characters to participate in chapters in an array (0x9ED64C) already. This (fairly small) array consists of the character being forced, the mode, and the chapter.
Also, there is a short list of four bytes,
02 19 0B 1E , immediately after this array. I suspect these are the characters that will display in cutscenes even if they are “killed” in gameplay.
EDIT: Spoke too soon about where the “Wounded at…” endings are located - table in charge of those is located at A3D2C0. Nightmare module
The weird numbering of the options seem to be because “Wounded and left the party” was dummied out from FE7 (although a little assembly could easily insert more options for this text.)
[CEE7A0 in FE7.]