I've accidentally given a legacy child the wrong name. I know for older Sims you can change their name at the town hall, but how would you go about this for a baby or toddler?

I've tried changing the name via Edit in CAS with Master Controller, but that didn't seem to actually change it.

i chose an adult and select change name on town hall. then you chose the toddler/baby. or, i believe that MasterController has a function to change name (without editing in CAS)

With master controller, click on the Sim, Click Master Controller>Basic>Rename to rename.

I've seen the option for a sim to change either their name, or their child's name at the city hall. I don't think that requires MC.

For this to happen, the following need to be true:

- The older sim selected must be a parent of the younger sim.
- Both of them must be in the same household.
- The younger sim must be a teen, or younger. If they were YA themselves, you would just select them.

That's true, it doesn't require MC. But the OP said she tried using MC's Edit in CAS function to change the name, and if you already have MC installed it's easier to use that than going through City Hall.