Hi, welcome to the ehealth forum and I am glad to help you.
Pediasure might be a good nutritional supplement for your 8 year old daughter but it cannot substitute for healthy and balanced natural diet which is so planned as to contain all the vital nutrients, minerals and trace elements.
As far as the height of your child is concerned that depends upon multiple factors besides nutrition such as parental height and has polygenic inheritance.
Hope this helps. Take care.
Note: This answer is not intended as and does not substitute for medical advice - the information presented is for patient education only. Please see your personal physician for further evaluation of your individual case.