Don't feed them the vitamin powder!!!!!
that can wait till your sister comes back, its also a terrible feeding method.
did you give them enough?? did you give them to little?? are they eating it or eating around it?? glider gravy has the vitamins they need.
You can cheaply buy more carrots, cucumber and apples from a local store, organic if you prefer. cost you about $4 for large bag of gala apples, the gala version is listed as preferred on the list I have from critterlove.
Sounds like you mixed the glider gravy correct. BUT PUT THIS IN A SEPARATE bowl all by itself, this way you can see if they eat it. it is also the MOST IMPORTANT FOOD as it has the most calcium and other stuff for them. the "glider chow" is fine to leave in cage for about 3 days, but ours eat very little of it.
I think you should buy a frozen bag of mixed vegetables, got the carrots, green beans, corn in it, give them a small amount of this, but if it is new to them its very likely they will NOT eat it for weeks or months at first. but the option for them is good. small bag $1.00 about, large bag $2.39
Put your hand on OUTSIDE of sleeping pouch, LET THEM CRAB, feel for them moving around, if they move around then you are probably fine, if deep sleeping they or one may take awhile to move around, you may have to move them alittle to wake them, do this once then leave them alone.
At night have it very dark, so they will come out of sleeping pouch, if its to light they may want to stay in pouch.