Grey Meadow, the Industrial Hub

I'm actually thinking of not making this a normal update and making this next version of the world take place ten years in the past before some sociopath set a number of the buildings on fire and before the entire Foster family was killed (well, their ghosts do not appear in the world, but they are buried in the back of Grey Meadow Manor). Does anyone know a way to age Sims backwards so that I do not have to recreate everyone and re-add them to the world, or perhaps not abandon this idea entirely? Editing Sims and changing their age in CAS is a bad idea, so do not suggest that please.