I Am A Caregiver. My Patient Has Been On 4

I am a caregiver. My Patient has been on 4 100mcg of Fentynal (Mylan) patches for 12 years. Her family practice doctor has been tapering her dosage for the last three months. (400 to 350). He is giving nothing else and will not allow anyone else. She was diagnosed with chronic and depression since 1997. Other doctors have ordered 500, he is taking her off. Is there a proper protocol for doing the taper. Thank You