Press Ctrl+Shift+C and type in "moveobjects on". go to Save, and save the game. Go to Buy Mode, and select the sim you DONT WANT TO AGE AT ALL, and delete him/her(them), but don't delete the sims you want to age. when you have deleted the desired charaters, turn free will on in the options bar. Press fast forward, and the sim(s) will take care of themselves until you have them at the desired ages. then save, go to nieghborhood, and click your sims house, the UNaged sims will be waiting at the mailbox.