If dad gets remarried who is over him? His new wife or his POA?

You will still have POA duties, unless daddy decides to change that.

Read the POA document carefully to understand those duties. Generally the POA simply allows you to help your father out in handling financial affairs. If he wants you to write the checks to pay bills, for example, you can do that. Generally the POA does not grant any authorization over his person -- for example, where he lives, what he eats, etc.

Do you also have medical proxy? If so, read that document.

Remember that your father can change POA and medical proxy at any time.