I don't understand. Are your parents wishing to change their health care proxy? You cannot do that for them. They must make those decisions. Are they capable of making new decisions for themselves? Do they want to change end of life measures, heroic measures and etc. or do they want to change the person who is acting as their proxy when they are no longer able to?
Can your parents understand what is happening? Can they speak with the attorney and make their wishes known? Because you cannot legally change anything, it must be them.
If the current situation is detrimental to them and their well-being you would have to pursue guardianship to have authority.
Are your parents wishing to change their health care proxy?
You cannot do that for them.
They must make those decisions.
Are they capable of making new decisions for themselves?
Do they want to change end of life measures, heroic measures and etc. or do they want to change the person who is acting as their proxy when they are no longer able to?
If the current situation is detrimental to them and their well-being you would have to pursue guardianship to have authority.