The girls are Elric twins. Elric. Twins. Considering how the non-twin siblings coordinate, it's a nightmare to realize how much the twins can coordinate when they're not being typical six-year-old girls.
Given a mission by their dear ol' uncle, they claw up from the tangle of snow and limbs they'd gotten themselves into and charge at the first one to fling a snowball like a single unit of Rugrat Terror, flinging poorly made snowballs as they go.
Edward could get used to having his own personal midget army.