The sale agreement made through Rs, 100/- stamp paper with advocate notary drafted & signed

I have taken one land in village though sale agreement on Rs,100/-stamp paper in 2011 which is drafted by Advocate and notary is signed . Measurement = 1200 sqft , sale amount is Rs,220000/- party sold to me by my mother in law’s brother which we are relations through my wife hence it understandingly made. From beginning to till now they are insisting us to come and construct your house instead to live in rent house . In this view I have migrated from city to village area completely with my family 6 months back. Now after 9 years village area is developing . Hence , his two sons are not ready give the property or not ready to make register instead they are asking 10 lakh from me OR Other wise they are ready to give 5 lakh to me to leave the property. We are made the Time condition in the paper is "Vendor is agreed to execute sale deed as and when called by the Purchaser ie, after getting katha in this name , Hence there is no any time for this agreement of sale." Vendor family members all are signed in agreement except last son at the time he is 10 yrs old. My Question is is that My sale agreement with Rs,100/- stampaper drafted and signed by Notary is valid to put up the case. Or Shall accept the 5 lakh Since Iam the poor family staying in rented house with small kids which Iam not having capacity to give 10 lakh. Request suggest & show the path to proceed int this matter. Thanks & Regards Guruswamy