I don't imagine it will ever be easy for a shorter, more solidly built person to look at a tall, lean one and not feel a little envious, but that can still be our goal. It is also wonderful to hear that your daughter is active. A lifetime of activity is the best way to prevent becoming overweight. It also is a great way to arrive at a mental attitude of feeling fit and full of energy. If you combine your daughter's active lifestyle with a wholesome, low fat diet you are setting her up for a successful attitude towards and acceptance of her body.
Snacks are an important piece of any diet, but especially for one who is hypoglycemic.
Snacks should make a positive contribution to the days total diet, and should not be looked at as an 'extra'. That means you want to use the same criteria for choosing a snack as you do for choosing a meal. In your daughter's case, you need to be sure that she try and keep her blood sugar up, and at a constant level. That means choosing snacks that will not result in rapid rises in blood sugar which are apt to be followed by a rapid fall. The best snacks are ones that contain protein and complex carbohydrates.