Both Erica and Sarah got hit with the spray and the rest was used. Shortly afterward they both felt changes happening. Their clothes first disappeared and they were standing their naked, and shocked.
Erica started shrinking. Her boobs started to shrink back into her body, butt started to shrink in size too. Then she lost her curvy hips. Her hair thinned out a little and became just a little shorter. She also gained some baby fat as she stopped shrinking around the age of two.
At the exact same time whatever was happening to Erica, the opposite seemed to be happening to Sarah. Sarah first started to get taller. Her chest was also pushing out until she was had small B cup boobs. Her butt got a bit bigger so she had a 'killer' ass, and her hips widened to form her curves. Her transformation completed with her hair thickened some and growing down to her shoulder blades, and she stopped at the age 15.
Then...