I also bring my son to travel this month and I found I would "trust no one". Once you have this in your mind, you will never let your baby "outside your finger".
It must be very carefull to bring a child to China. Did you see the beggars in the street? I will not bring them to China. If you loss you children in HK, normally you can found them, but in China......
I try to keep 100% attention to them when bring them outside but I still have an experience to loss one. I help my son(7years old) to try a new shoes in Citistore while my daughter(3 1/2 years old) stands beside me. Suddenly my son ask me where is his sister. That day is Sunday and it is very crowned. We can't found her. I shouted her name loudly and the people looking at me. Some people say they saw a girl shouted loudly for mother. At last I found her in the security room because a couple bring her to. When my daughter saw us, she cried and cried. I am so scared and I think I will pay 200% attention to them.