Unfortunately your diet is not balance, you need one that includes a proper protein staple. Pellets are not adequate and should not be used as a main staple. If you go to the gliderpedia section, you can look through some popular diet recipes and find one that works for you. A glider's diet should consist of 50% protein, 25% veggies, and 25% fruit.
Sprinkling vitamins on food is also not recommended, it is much to easy to overdose them this way, which is another reason you will want to get on a specific plan. That way you will know all of the nutrition they need is provided, without having to guess. In the mean time, begin offering them some boiled chicken or plain scrambled or boiled eggs (with no seasoning) for their protein source along with the fruits and veggies.