I think it's safe to say the Bug is due for a nickname change and the best candidate I have currently is The Enforcer. Considering that I've already described about 123,482 personality traits of an oldest child I'm sure you can guess why I'm considering this particular nickname.
She has already gently redirected
scolded Ava for:
-Screaming in the house.
-Chewing on crayons (provided by her of course)
-"Playing" too close to the fireplace.
- Chewing on books
Given those are all legitimate offenses around here AND they are all still offenses regularly committed by the Bug herself, she is still having to learn that she is not the boss around here...