I know this has been dead for some time but I thought I should throw in my little comment if you, like me, came here to try to clear something up about the age up cheat. I haven't tried this in my fully patched game with all Eps and stuff packs minus Into the Future and Island Paridise...and frankly I'm too afraid to try it again.
When I tried this I was under the impression that it was ONLY during childhood and that once a child was aged up or transitioned they would become fully playable again. Well that was not the case when I tried this. I ended up losing a WHOLE generation and ended up having to scrap my genetics research project because of it...and by 'WHOLE' generation I mean that my female sim had a child with EVERY male sim that looked like they had decent genetics in Sunset Valley. Unfortunately I was unable to see how the genetics played out in the second generation because in order to have so many children and not kill them I figured I'd use this cheat to allow me to focus on the baby making. Well that was not the case. I had lifespan on short but the kids never seemed to age up, then when I found out that you could age them without a cheat using the birthday cake I tried that...but they were still NPCs! I tried to age trigger using a cheat but they were still NPCs that way too. I then figured that maybe it was for childhood/ teen years. So I aged them up to YA. Still nothing- they were still NPCs. So I tried adult...still NPCs. Then I figured maybe if I kill them I would get the Oh My Ghost Op and then I could gain control over them. Well I waited until their mother's death and still never got the OP.
SO if you do try this...make sure to save your game before and TEST IT!! I've never heard of anyone having the same problems as I did- but it's a lot better than finding out the hard way at least.