Let me break it down for you: Each individual has a set of protein markers throughout the body that tell the immune system "This is me." We find a "match" for a patient that has the most protein identification markers on it that are as close to the patient's protein identification markers as possible. Before, during, and after the transplant a patient has to be on drugs that keep the immune system from poking around the new kidneys and saying "Hey, that doesn't belong here so I have to kill it to protect myself!"
When the immune system decides to kill the new kidneys toxins will no longer be filtered out of the body. These toxins build up in the blood stream and are circulated in the blood to poison the rest of the body. Given enough time the rest of the body will shut down such as the liver, the lungs, the brain, the heart, etc. You have essentially put your child into the land of slow painful death.
Congratulations! You're a murderer whose reckless stupidity sours my mayonnaise!
***Update: On a happy note the child turned up at a hospital in a different state. I hope she gets the best of care and her dumb ass parent goes to prison.