Your rights to be informed of, or participate in decisions regarding, the care of your mother is a matter of the law of the state in which she lives. Nothing short of a consultation and maybe representation by an experienced elder law attorney that practices near where your mother lives will meet your needs.
Best wishes for an outcome you can accept, and please remember to designate a best answer.
This answer is offered as a public service for general information only and may not be relied upon as legal advice.
An elder law attorney will help you protect your rights to be involved in your mother's affairs.
My comments are NOT LEGAL ADVICE. They are for informational purposes only. Actual legal advice can only be provided after you have signed an engagement letter. Answering this question does not create an attorney client relationship. Remember that without attorney client privilege you could possibly divulge information that can hurt your legal rights in the future. I am a tax attorney in Miami Florida. I can help you with your federal tax issues via a secure client portal if required.