It is called the Baker act in Florida, but all states have laws regarding persons believed to be a danger to themself or someone else, and mental illness. It involves a court order to admit them to the hospital involuntarily.
Usually, they are kept for a period of time, and there is then a hearing to rule on if she needs to be kept longer.
Any release of information is under HIPAA, which is federal law, not Fl..they are not allowed to release anything, unless to parent of a minor. People in psch hospitals are especially vulnerable to this, since there is stigma.
I don't know if this would work. but you might call the hospital, and make it clear that you are NOT asking for info, since you know you cannot get it. However, you can ask to leave a message for the staff (her physician), that you are a concerned relative, and available for help if needed. You are not prohibited by HIPAA from GIVING info. just getting it, without consent.