Yes, I’ve had plenty of experiences with both the power struggle with a parent and refusal to cooperate and comply. I suggest being as patient as you can with your father by explaining in detail the benefits of cooperating to improve the caregiving experience for you both.
In terms of the medical compliance, including a health care professional as a neutral 3rd-party member in your conversations may create more willingness with your father to adhere to doctor’s orders. Please note that getting a legal healthcare proxy is required for any type of decision-making regarding your father’s care.
I recommend reading my blogs: “How to Deal with Your Mother’s Refusal for Health Treatment and Try for Consent” and “6 Essential Legal and 11 Non-Legal Documents for Your Caregiving Toolbox”.
Good luck and I hope this helps!