A friend told me about this several years ago and it might help on both sides of this.
Make a 'home sick' bag for your daughter when she leaves and she can make one for you too. You take a big, pretty bag (or box) and fill it with gift wrapped trinkets, photos, favorite snacks, miss you and thinking of you cards, phone cards etc... and give it to her when she leaves. The idea is that everytime she gets homesick she can get in the bag and open a gift and think of you and the love it was sent with and maybe it will help ease the pain of being homesick.
