How to add days onto the age of a sim?

[KiwiPriss]

My oldest child in my legacy was four days from becoming a teenager... when I changed his hair and closed, and he snapped back to being 7 days from aging, the same as his younger sister. Help?? Don't want him to be the same age as her. Is there any way to change it?? I don't mind cheating as I think that qualifies as fixing a bug

[Mikkey]

I have the same problem although I don't know what caused it (I thought it had to do with them coming back from vacation, but I'm not sure). Both my teens were the same age all of a sudden (and yeah, it's something that really bothers me)

Tasha, I play on epic lifespan and don't want to age anyone anytime soon, I gave his sister a life fruit to eat so she's a bit younger again, but don't want to do this again as I don't want her to be significantly younger than her friends either.