Your question about what a principal wants and what the grantee wants should not be at odds. If the owner tells you he doesn't want to sell, but you have the power to sell, you may wind up with more trouble than you bargained for. I think that's the question you're asking: can you the holder of a general POA sell a property that you know the principal wants to keep.
My strong suggestion is for you to seek counsel about the legal aspects of it, financial advice on the tax aspects, and other family members for their guidance on what is best.
Good luck with that.
Nicole Marks Mason, Realtor
Lynn911 Dallas Realtor & Consultant, Credit Repair Advisor
The Michael Group - Dallas Business Journal Top Ranked Realtors