Reset sim age?

I apologize if this has already been mentioned. One easy way to take control of a sim temporarily and not change households would be to go into edit town and merge Alexander in with your sim's household, then play the household, and have him drink the potion. After he has drunk the potion, go back into Edit Town, and merge him back into his former home. Now if for some reason he lives by himself, what I do is before I originally merge him with the other sim is to find another household that has several sims in the household, and merge one of them in with him. This will keep the name and family funds intact. Then after you are completed with what you need to do, then merge him back to his old household, and after that merge the other sim back to where they came from.