vende refuse to come on time for registration

This is the fourth query you have posted to day.  It appears that you are not coming out with facts.  It is presumed basing on advance of Rs.15 lakhs given out of Rs.80 lakhs the purchasers are trying to get occupation of the land.   You can not get any remedies by this piece meal , incomplete queries, and the only way is to approach to a local advocate with your legal heir certificate, valid title deed, mutation, previous injunction order obtained by your father for such NGGO society plot, facts of such sale transaction of Rs.80 lakh with your white paper receipt for Rs.15 lakh etc.

Think practically.