The incest patch, as with all patches / mods to the game, is not official, and the game will detect that the config file is changed and make sure you're aware that any changes made are not supported by NLT. With that said, it's "debatable" whether Valerie is intended to be the MC's mother or not, and it is likely due to Patreon rules that she is not. (So the intent is such that Valerie is the MC's mother.)
While I know the game works with or without the patch, I would say that using the patch likely gets you a more canon experience. That goes for basically all games with an incest patch - if it's there, install it, because typically things make more sense / are smoother. (Because really, how many people live with their land-lady and their daughters, right?)