Bbmp land registration

Dear experts, I seek your aide and advice on a property matter. There are two piece of land . For both pieces of land the owner has a possession certificate only. She does not have a sale deed done through the bbmp. The possession certificate has a condition that the land cannot be sold or leased for 10 years. Both pieces of land were brought through POA, because of the condition in the possession certificste. My humble question is. 1) can the POA holder sell the land and sign on the absolute sale deed in the registrar's office on behalf of the owner, will this be accepted in the registrar's office. 2)can the buyer take that sale deed and approach the court for a declaratory suit. 3)can the buyer directly go to the bbmp and request for a kata based on the sale deed on which the POA holder has signed without going to the court and filling a declaratory suit.