She needs to be on a balanced staple diet. Especially at her age and already at a disadvantage from being removed from her parents so early.
Sprinkling calcium is risky, to much can be just as dangerous as not enough.
I'd suggest you do some research on diets, the two I recommend are Bml and Critter Love. She really needs a sound, balanced, nutritional diet to give her a better start at maturing and developing.
http://www.bmldiet.com/bml-recipe.html
http://www.critterlove.com/diet-info.html
Gaterade and pedialyte are only usually only used when a glider is dehydrated or is ill, she is better off with straight water rather than adding either of those to her normal drinking supply.
Please keep in mind she is pretty young, young joeys tend to grow into their fruits n veg so she may not eat many things you offer her right now. Many don't like banana's ( mine won't touch them ) sweet potatoes should be cooked not raw. Getting her to eat things your offering may be even harder because her parents didn't have time to teach her to eat big kid food.
I have a 5 week old joey right now, she is justtttt starting to go to their food plate to eat big kid food, she follows her mom n dad or gets a ride on their back to the plate. ( keep in mind this is prolly how old your joey was when you got her) My joey is eating the bml and a little fruit but not going anywhere near veg yet, and really she is a little early to be eating big kid food, some don't even start to eat it til they are 7 -8 weeks old. Most ethical breeders won't sell joeys until they are 10 -12 weeks old for this reason.