Question: "I was given sole custody. I know that means I have full control over where my child goes to school, goes to church, goes to the doctor, etc. My ex has asked the school to send my child's grades to both of us, not just to me. How do I make the school send the grades only to me?"
My first question is, why would you want to deny your ex that information? Putting a block between your child and your ex will almost certainly backfire on you. Your child will most likely have a great difficulty understanding why you took a step, however small, to alienate him or her from your ex. Your may distrust your ex, fear your ex, even hate your ex, but your child probably doesn't. Your child, at any age, probably wants a relationship with your ex. I realize there are exceptions to this rule, especially at the older ages where children often become less attached to and dependent on their parents, but you should stay out of it. DON'T DO ANYTHING TO DISTANCE YOUR CHILD FROM YOUR EX unless you have a really, really, REALLY good reason. Like maybe a court order or a provable fear of harm to your child. Notice I said, "provable."
And most judges won't back you up if you try to keep grades from your ex. Florida judges are very reluctant to prohibit a parent from seeing the grades of his or her child. Judges do what they can to unite children with estranged parents, and they are very reluctant to do anything that separates children from their parents in any way unless there is evidence of child abuse or some other direct harm to the child.
But that doesn't really answer your question, does it? Despite my warning, if you want to keep the grades from your ex, you can probably get away with it. Show the principal your "sole custody" order, and the school will probably send the grades only to you from that point forward. Your ex may complain to the school, but most school officials would recommend to your ex that the matter be taken up in court. Then they'd continue to send the report cards only to you. Keeping grades from your spouse may be wrong, but you'd probably be successful. Now that I've answered the question, I can only hope you'll use your newfound knowledge for good, not evil.