I wouldn't write anything, I'd call the cops. She knows very well she's disturbing the whole house and couldn't care less. One birthday party is fine, I guess everyone deserves that but repeated noisy parties are not.
In my country the law says there are rest hours between 10pm and 8am, and 1pm and 2pm. That is the law and if you don't respect that, you can and are fined. We're still in state of emergency, there's a curfew, so gathering people in your house is treated like a criminal case.
Now that she's been notified and knows her loud parties are not welcome, next time call the cops. Looks like she needs to learn the hard way as she has respect for no one.