Flavia is old neighbour of MC. Who appeared later in a few renders. It is not LI. All this means is that you haven't played the game or read the dialogues.
I think yea from my part i think i was wrong i replayed it and yea the dialogue it hints that way but i think is not ntr ,this guy is just talking nonsense don't listen to him .
What models do you use for this ?
Make the story and game the way you intended too.
Just small warning if u use patreon they don't allow incest so they can delete your account without warning use subscribestar better it takes longer to be approved,but is better regarding that kind of content or change the dialogue.
All in all the game is not bad is different so keep it up and again gl .