Comparing sizing to RTW?

Hello all! I am getting ready to start in on costuming for an ice show - which is what I do full time, make skating apparel that is. This however is for a benefit ice show so I'm looking for a few shortcuts. ;) I'd like to use the Sunny Day Shorts pattern as a base for most of the skaters in one number - they will have blue sequin shorts, yellow polo tops and blue caps - sort of a "scout uniform" style look. 3/4s of the skaters are child sized and I have waist and hip measurements for all. I'm just wondering how close the Sunny Day shorts run to RTW sizing? I've made them once before in size 2 and found them a bit big but that 2yo may just be tiny. I am capable of altering the pattern/grading if needed, just thought it would be easier to have a starting point. Thanks! Oh, my fabric has a bit of stretch but I don't want the shorts to be a fitted dance short look.