Actually I have exactly that planned... there's some preview screenshots over in the new Hi-Res Bodyshape section of a S, L and XL sizes for both top and bottoms for the teens, which will be incorporated with the suitable sizes for the adults in the skintones. Adult-Teen will be A=A, D=C, DD-DDD=D for the tops, 32=S, 36=L, 38-40=XL for the bottoms. Here's a link to the screenies:
Teen BodyShapes