@luftspeiler - Oops, context failure error here. Sorry, what I meant above was total absolute age. The total number of sim days that a sim has lived. If it's 1,400 sim days before one fiddles around with the age spans in Game Options, it' still 1,400 when finished but the sim might now be in the "wrong" stage for their total age.

On the two MC settings, a 4 in Absolute will make the sim 4 sim days into their current age stage no matter where they started from. A 4 in Relative will be read as "+4" and add four to their current age, at least that's the way I think it was supposed to work. They each have different uses.

Thanks for that explanation igazor. I use Absolute age to make them younger usually. So if I have a sim that is an adult, I can't take them back to being a YA without going into CAS, however, I can make them at day one of being an adult, which is acceptable to me for what I wanted to do.

About (possible) "breakage": What will happen if I edit a service/role sim (non-resident) in CAS and change their age stage from Adult to YA? This makes me curious, I have not dared to try it, and have no need whatsoever to do this on my precious residential sims.

It's probably not recommended for some reason or another, but I've never had trouble changing any existing sims in CAS from Adult to YA or back. The other life stages not so much because the sims are different sizes/shapes and have other different things about them.

Sorry, I had to bring this question back again. I really don't like playing with this long a lifespan so I want to change it. I don't want to end up with a ton of sims all in the wrong age group or stuck ageing. My sim moves around a lot and I change her homeworld each time she moves which is approx 6 months to 1 year of game time (2-4 seasons). Now, if I were to move her to an unpopulated world, change the lifespan and them populate the world with RI would that be a better way? Now what about if she back tracks and goes back to some of the worlds she's lived in which are populated and had the long lifespan?

I don't really think you can have different lifespans in different worlds all within the same ongoing game save. I mean, you can try but the game won't really understand what stage each sim is really supposed to be in as they travel through and get pulled in to visit the different worlds. Hate to say this, but for that drastic a change sounds like you need to start a new game to me.

Ok thanks igazor, I'll just play this out for now and change the lifespan before I start a new game. With this lifespan, my sim will probably outlive me LOL.