I was recently asked on my tumblr how I enabled custom eyes for toddlers. The easiest way to do this is to go back to the creator and see if they updated them. If they are no longer active, then you can follow the below steps (note: that this will also work for skin details like freckles, moles, blush, scars but not full body skins).
Version 1 (the easiest one):
Open the package with Sims4Studio and then navigate to categories. Right on top, there will be a toddler box. Select that and then select apply to all swatches. You might get a pop-up message that says something about it needing to be updated. Select OK (or yes, I can’t remember which one it says). Select a different eye color to make sure they all have toddlers enabled.
Scroll to the bottom and save.
Version Two (the not so easy one):
You open the package and you see the below. Without getting into all the details of the differences between the two, it can still be enabled for toddlers. It just takes a little more work.
So, what you are going to do is select the line that says “CAS part” and then click the box that says “toddler”. You will do this for every single CAS part. This is why I said it’s a little harder but just because it’s tedious.
Once you’re done, save the package and viola!