I take care of my parents who are in their 80's dad has no issues of me knowing anything about his meds, mother refuses me to go to any of their doctor appointments, the doctor has been adjusting meds and I don't know why. I don't know how they are suppose to be taking them or what they are suppose to take, I do have a list of all the meds and have done research but I didn't know the meds they are taking are for medical issues I was not aware of. Last doctor they had, I went to as many visits as possible. But since then they have a new one and I have not attended one. I was on the list from the previous doctor of getting information, I have no idea if I am able to do this now.
They really should have a Power Of Attorney drawn up with you or someone they trust as a representative. When they do this, they should have one drawn up for health, as well. That document should include the appropriate HIPAA language that would allow you to not only attend your mother's appointments, but help her if she and your dad are both incapacitated. If you can let them know that this is normal procedure, maybe you can talk them into it. If you think that your mom will fight this, see if one of their contemporaries - a long term friend or relative - could help them see the necessity of this move.
Good luck to you. This is the frustrating unintended consequence of the privacy laws.
Carol