Sim De-Aged

She's in the gallery under De-Age Sim Issue, thanks!

She's a pre-made, her name is Alex, but not sure her original last name, she married my sim. She has no family tree either.

@lisastar08 Thank you for uploading Alex. I have been chatting with @EuphorialQueen & @CGrant56 and they both have some ideas on this that I think are very helpful (plus I'm not feeling well) so I am tagging them to see if they can add some light to this. I'm told that Alex Moyer is in the tutorial and is a Maxis sim that is set to never age and never die. EuphorialQueen has played her in the tutorial, and CGrant56 has played with MCCC. 

Edit: I did download your Alex and had a roommate bake a cake and add candles, and the other sim got the option to blow out candles, but Alex does not have that option. 

@lisastar08 

I took a look at your sim and the original from a new game as well.  In a nutshell, the aging problem is caused by Alex (Moyer is the original surname) being a special sim that is used in the tutorial.  She has the hidden trait:  trait_SpecialNPC_isFTUERoommate which adds Disable Aging and Disable Death to the sim.  That explains a lot about why she has aging issues as the game wants to keep her a YA with a set number of days in her age group.  Probably so that she will be there if players rerun the tutorial.  It's a guess though.

I did some further testing and like @SheriGR neither the original from my test game nor your Alex get the Blow out the Candles option on a cake to age them up.  But I also went into CAS and created a clone of her.  Actually, I used add a new sim through Play with Genetics and created a twin for both the original from my game and your Alex.  The twin is not exact as it had different clothes and hair and her size was a little different but those are easy to change.  If you use the cas.fulleditmode cheat before you take the household in CAS, you can also deal with the size difference by using the sliders.

MCCC does not have a way to edit the hidden traits, only the original 3 that the player can assign at sim creation.  In fact, MCCC does not even see them.  I use a mod called ShowSimInfo by Itasan2 which you can find at MTS to see hidden traits.  That mod can't change anything.  It just shows all kinds of nice to know info about a sim.  It's a nice complement to MCCC.

But in the end, your situation comes down to the Alex sim in your game.  The only way I can think of to fix the problem is to clone her by creating a twin in CAS and then manually copying her clothes, hair, makeup etc. there. (You can also use MCCC to copy all the appearance things but I haven't tried doing that so I don't know how it works.  I just mention it so you know the option exists)  If you have the cas.fulleditmode active at the time you create the twin, you can also address her body size and traits.  Then delete your Alex and rename the twin.  Then you can use MCCC to set the skills to what your Alex had and if necessary, set any relationships that you couldn't in CAS.  MCCC will also let you change days in an age range and other things to get the new sim as close to the old one as you can.

So If you choose to go that way, I suggest you make notes if you want to duplicate the sim to get the new one as close as possible to the old one since there's a lot of things that will need to be changed.

Anyway, I hope this helps you.  

@CGrant56 Thank you for all of the awesome and helpful information!!

@lisastar08 After sleeping on this I won't know what I was thinking to not also mention that since we now have confirmation the this is a 'special' sim and is forcing itself back to the age it was designed to be... I suppose that another option could be to go CAS and edit the physical traits of your Alex so that she looks older, even though she is not. Add wrinkles, grey or semi-grey hair, whatever will make her look the age you want her.

An example of doing this is Vlad, from the Vampires pack. If you look at the screenshot below he obviously looks like an elder, but if you look at the sim age area at the top left he is actually a young adult:

@lisastar08 

@EuphorialQueen Just pointed out a method she used to age Alex so I thought I'd share it here. You would have to see if the age sticks, but it's another option:

1. Have Alex or a roommate make a cake and put candles on it. Immediately save and exit. 
2. Now Enter the lot with another sim. Have that sim click on the cake. scroll through all options until you find 'Age Up Sim'.
   
3. Click 'Age Up Sim' and you should see Alex in choices. Pick her to age up.
   
4. She should then go to the cake and blow out the candles. 
   
5. If you then enter CAS with Alex you will see she is one age group older.
   

Thank you all for your help, I'd never heard of sims like this before, and definitely makes my gameplay a challenge since she was already younger than her son and outlive her family that she had after marrying my sim.

I was able to age her to an elder via the cake trick it worked perfectly, thank you so much!!

Will I still be able to kill her via drowning or fire when I'm ready? 

@lisastar08 Glad that @EuphorialQueen's workaround worked. No, I would say she cannot die given what @CGrant56 had said about her hidden trait of not dying.

Oh no, cause now she's going to out live her son, grand children and so forth and mess up my family tree 😞

@lisastar08 You could follow @CGrant56's directions (comment #15) and make a twin of the sim, etc. and use that sim instead.