I noticed! I have a feeling the actual author is saying they are the little sister in the story
waitt where does it showw which chap?? that's so cutee
which is kinda funny considering you can actually see yi kui and lin you in the background in one of the extras of dont say you love me
WAIT WHAT? WHAT CHAPTER DID IT SHOW
Not only did it show (I forgot chapter but it was somewhere where the little sister was in class with her friends) but I think they talked about it too because there is the second couple ig and the green femboy stopped her from spoiling what she wanted to drew more to her friends (green femboy doesn't like spoilers)
Maybe some of you haven't realized or saw but Mc's little sister is creator of Your Dream Is Delicious, which is other art of the author cute detail