Unregistered document is inadmissible in evidence, but can be used for purpose of filling suit of specific performance. Property inherited from father, legal heirs bound by the agreement executed by father.
But here money was to be paid within one year, and if he not than agreement already lapsed for non performance of buyer.
Even if money was paid in same year, than also suit bar by limitation. Cause of action aroused in year 2000 and limitation for filling suit is 3 years.