This raises a lot of 'but what happens if we don't?' questions in me. If it's dormant but unharmed when we don't feed kids to it, why are we feeding kids to it? If we're worried about it ageing, why aren't we trying to keep it fed on younger kids to see if that stops it?
As of ██/██/████, the next corpse will need to be a child of seven years of age.
This line in particular is really weak. "Yeah, Bob, we're gonna need a seven-year-old child, so if you could get right on it that would be great." Say that the next corpse will be a seven-year-old child, and it becomes the creepiest bit of the entire piece because it sounds like they've got one picked out already.