Legal Question in Family Law in Virginia

Re: child custody

No, you've been given wrong information, i.e., the boy cannot "go to court and decide for himself at the age of 12" the issue as to which parent should have full custody. Such a determination can only be properly made by a court after considering all of the relevant factors in the case and which would form the basis for a best interests of the child determination by the judge hearing the matter.

The custody suit would be filed in the jurisdiction where the boy currently lives and this is a matter for which you will obviously need the services of an attorney in order to have any chance of success.