3 year overstay

My adult son has overstayed his visa by almost 3 years. He is an alcoholic, and had a fight with us, and he left. I have been searching for him, and he has resurfaced near Shenzhen. I have made plans to take him to alcohol rehab in Thailand. We plan to fly out of shenzhen airport directly to Thailand. Is our best option to surrender him to th immigration people after we check in for out flight? He cannot be detained, as he needs immediate detox......I am prepared to pay 10,000 in fines. Will they let us pay, and board our flight? Thanks