If you're plot resetting, is there any part of talking to Isabelle that's safe? Can you talk to her as your mayor as long as you don't get to the Preparing Your Town screen, or do you have to avoid her altogether? I have a ninth villager moving in, but I want to demolish my two secondary characters and I don't know if that will set the plots for good. Also, just wondering if you can change the time without setting the villager in stone.
Until I get an answer, I'm just creating a fourth character. First villager: Rodney. Reset!
Edit: I still would like an answer, but I'm an idiot. A lucky idiot, but an idiot. I decided to risk demolishing the secondaries but got distracted and loaded up the game as one.
Luckily, there wasn't a plot at all. Unluckily, that means my plot resetting fun is over for the day.