Yeah, one thing about this game which in most cases is a service comes to your hindrance here: once you started a game with the patch, Stacy will stay your sister so you don't have to download and "install" (copy) the patch with each update.
There probably is a console command I don't know to change the relationship status but this save is "contaminated".
That would be as simple as reversing the contents of the script i'd imagine.
So for example the
taboo.rpy file reads:
Python:
init 4 python:
set_special(True)
is_antagonist_mode = True
So my assumption is you would simply have to change it to
Python:
init 4 python:
set_special(False)
is_antagonist_mode = False
Then just run the game once and then you can delete the file as well as its corresponding
.rpyc file. Although more complicated it would be a potentially better option for those with slower internet connections. But this is only really faesible for this simple style of patch, more complex things like the multi mods would be harder to remove manually. What I tend to do for this is keep a copy of the original game archive, which is the most optimal solution if you can spare the space. That way you can just re-extract it.
Also will note that if my assumption about reversing the script is wrong someone please do inform me, i've coded in python for nearly 9 years now so i'm plenty familiar with it but idk how different renpy stuff is from core python
