This is not possible with a enumeration. As this is a hardcoded list in your model.
Of course you can hack a bit using the DynamicEnumPicker, but I have the idea you need something dynamic. Which a enum isn't by definition.
If you want to have a dynamic pick list. Use a referenced entity, with a list of records matching the required values.
Try the DynamicEnumPicker widget, where the user can choose which values of the enumeration to display and change the captions of the enumeration values
Hope it helps!!!