1. Your query is silent on whether the power of attorney has been registered or not. There cannot be a sale without consideration. Therefore, the principles of agency coupled with interest shall not apply. Such Powers of Attorneys in absence of consideration are revocable and can be unilaterally withdrawn.
2. A POA stands cancelled after the death of Principal, so if there is any transaction by the POA agent subsequent to the death of the Principal, it is illegal. Limitation of POA is death of either of one i.e Testator or POA holder, or cancellation by testator, whichever is earlier.
3. Legal heirs of the deceased owner can execute the sale deed in your favour to complete the sale.
4. POA cannot register the property in favour of wife or any blood relative.