I have never heard of this product before. You might contact Peggy and ask her if she recommends that this be used with her HPW Complete or HPW Plus diets.
I am not sure joeys need the "Powerful Antioxidants" this berry powder is described as. Joeys generally follow their parents to the food dish to learn to eat other foods as they are naturally weaned by their mother. I do not feel any supplements are needed for joey weaning.
The owner of the web page is a vendor for Peggy's products - but also appears to sell a number of other items as well.