How do I get copies of prescriptions for mom?

concerned my sister in law who cares 24/7 for her mom for the past 7 years and does a great job could be continuing to get a doctor friend to write 190 hydrocodone a month. It has managed to be in court with siblings that suspect her medications and finances are suspect. Judge has allowed this testimony and wants proof if mom at 85 truly is taking that much. She has doa over finances. Brother has dpoa of health. Im concerned why she would be written a prescription for thag much but doesnt appear to be that sedated. She has been deemed incompetent with mid stage dementia. There is question as to why would a doctor prescribe that much to an 85 year old.