open the mod menu, go to game modifiers, then click game assets modifier, then extra level data, then select any style, click NPCs to spawn, click Add new element, then find and click on "Mrs Pomp". you can do this to any character too
for the subtitles, try adding this: go to subtitles_en and add the captions for NoL (Mrs.Pomp) like this: {"key":"Vfx_NoL_RemindingYou","value":"Just reminding you to be at my class in"}, and then all of them.
This should have NOTHING to do with the other captions.