Thanks for your prompt reply.
Now I use this to cut the 25 mg pill to halves and then make them to powder before divide them into 3 even portions.
http://img263.imageshack.us/img263/6324/20080608193as7.jpg
Franklying speaking, it is indeed the accurate problem you mentioned. However, I have discussed this with her doctor, and he said that I just try my best to divide them equally. Therefore, I will try if I can find any smaller pill, like 5 mg or 10 mg.
As for her growth, now she is 2Y_2M with 89cm (height: 15th over 100 w/ same age girls) and 10.5kg (weight: only 90th over 100 w/ same age girls). Her doctor didn't say anything wrong about her growth because she still follows the growth curve (height only...sigh!).
In fact, my daughter doesn't have puffy cheeks. She eats less but she is very energetic and naughty. I don't know if it is the reason why she needs to take 15mg per day? Now she will have blood draw for testing every 3 months.