Can I sell my parent's home if I have POA for both of them?

There is a will that names me as executor. I have a younger brother that left town over a year ago that I cannot locate. My sister is not in the will, Will specifically states she gets nothing. I am POA for both of my parents. My Mom has had Alzheimer's for over 7 years. My dad had a stroke over 2 years ago. He is ok mentally with a few physical problems. He wants to sell their home because we need it for Mom's care. The real estate agent wants to list for $500,000. Dad wants us to buy a home with us on another note together. He wants to give me a down payment. We would, of course, finance the rest. The rest would go to savings for their care. The realtor has asked me for the reverse mortgage papers, She said this is to take to her attorney to make sure the house CAN be paid off. We have already checked through our attorney and it can be. She wants a copy of the will. We are confused why? My parents are both still alive, and pretty well. Dad signed realty papers already.