The choice only appear when there's no people in the kitchen and before they have dinner which is around 6pm I forgot. So yeah, if the maid is in there, you need to set her alarm at around that and ofcourse you need to buy the drugs first.
Maybe you replace the save when you are still ingame?.
Pretty sure its in the main game folder.
I still don't know about the saves, the game was closed when I swapped the files, but I still didn't unlock anything from the CG, and my saves seemed to be there.
As for the pills tho, I cracked that. I was thinking about it wrong, thinking that you set the alarm late, then show up early and mess with the food before she starts cooking.
Instead you need to wait for her to start, then use the alarms as distractions to make her leave the half-cooked food unattended.
You also need to lure away the Aunt and the Cousin at the same time, because all three cook together. I set my timers for 18:30 or 19:00
The drug-options aren't translated, but top is aphrodisiac, the second is diuretic, third is sleeping pills and last is whiskey bonbons. (The latter doesn't seem to do anything, that I can detect)
it asks how many pills you want to use, but I just used the max each time. IIRC from the first game, 1-2 pills don't do anything, and I didn't want to fuck about.
Tampering with the food is a good way to get the blackmail material that you need during your first run. Especially for the last girl who only shows up on Thursday, since it's damn near impossible to catch her doing anything otherwise.