With cases of residence orders, the law is that from March 2005 a child age 9 yrs or over has a large say in who they want to live with. Given your son's age, I can't image any Family Court making him live with his dad if it was against his wishes. A friend of mine had a similar concern (she wanted her child to live with her sister if anything was to happen to her) and if I remember correctly she stipulated the fact in her will. I'm not sure what the law is regarding the CSA. I'd advise you to look into it for your own peace of mind, but I wish you a long and happy life!