Criminal Law Questions? Ask a Criminal Lawyer.
Dear JACUSTOMER - Since your daughter is an adult there's not much you can do except hire a lawyer if you can afford it. If you can't then she needs to get one appointed by the court since it will be based on her financial condition, not yours as to whether she qualifies for a court appointed attorney. She should not talk to anyone about the case except for a lawyer.
When she appears in court she should plead not guilty and this will get the case into the court system and give her attorney an opportunity to discuss the case with the prosecutor and the judge to explore the possibility of a dismissal or a reduction of the charges. If the cop didn't actually catch your daughter holding the open container then the argument can be made that the driver is responsible for the car and its contents, not the passengers.
Obviously I have not read the police report and I do not have all the facts but your daughter needs to remain silent and get a lawyer. Every defense lawyer in America will tell you the same thing.