Is Deed of Agreement for sale valid in notary without registrar ?

Dear Sir, In the year of 1997 a person sold the property through POA which is registrar with stamp fee. in the year of 2000 the PoA holder sale the property to another person through notary affidavit which is not registrar. the property belong to Housing Board was the 1st Party. Some dues are pending to Housing Board and when all dues are clear and NOC already been received, the Housing Board was suggest the revocation of PoA which was execute earlier in 1997. But at the time of year 2015 the PoA holder was died before 2 years. So the Legal hair and the 2nd Party i.e. who was the allottee of that home) are mutually cancel the PoA with produce of Death Certificate and Legal hear document. Then the Housing Board was notice that allottee to execute the deed in his favor and also the same may be done with in a week. But the good of honour the allottee wants to transfer that property to the party which is son of that late PoA holder. and the basis need of the husing board and all process should be done in his favor. the paper advertisement for notice of one month is published. then transfer made on that persons. Hence, the question is who was received the property in 2000 through a Deed of Agreement for sale in a notary affidavit without registrar was claim that the said house is in there name. and also they have physical possession in it. but the said house was locked before 2-3 years. Sir, Please give me some valuable suggestion.