What bothers me most is not the thought of your child destroying books but of you trying to fix them. I kind-of fix books for a living. I'm sure you are doing it wrong. You lack the proper tools like a bone folder and hinge tape. Also I doubt you've watched as many YouTube videos on book repair as I have. Bring them all to Mom and Dad's tomorrow and I'll see if I can repair the damage (not R's damage, yours).
Your Patronizing Sister, Kate