What can I expect at the initial doctor appointment to activate the medical power of attorney?

What can I expect at the initial doctor appointment to activate the medical power of attorney? We have been in touch with the doctors about my dad's abusive behavior and he has already been diagnosed with Alzheimer's. We have an appointment on Tuesday and the doctor said they are going to activate the medical power of attorney. I'm not entirely sure what to expect and I have all kinds of anxiety about it because I know my dad is going to be furious! He is already extremely abusive. Are they going to ask me questions right in front of him about his forgetfulness and his behavior? Or are there routine questions to ask him and just quietly sign it and let you go? I really don't know what to expect and I'm extremely nervous.