Agreement of sale com general power of attorney with possession

I recently purchased a plot in hyderabad by paying the full amount to the owner. The plot is in his name.. However instead of executing the sale deed, I executed Agreement of sale and general power of attorney with possession(AGPA) at sub registrar office at uppal. I had to pay the 6% as registration charges at SRO and the document is registered at SRO Uppal. I payed full amount to the owner and same is specified in the document. Let's just say owner is A and I am B, I have the following queries. 1) is my Agreement of sale and general power of attorney with possession(AGPA) valid even after the death of A(owner). Do the legal heirs of A(owner) have any rights as per law to claim the property or say that my AGPA is invalid after the death of A(owner). Would I be able to sell the plot to someone else after A(owner's) death? 2) What happens to Agreement of sale and general power of attorney with possession(AGPA) after my death? would my legal heirs be able to inherit the plot and sell it to someone else? is AGPA vald after my death? if yes then what is the process for my legal heirs to transfer the ownership to them