Is 100 rupees stamp paper is legally enforceable ?

On 28 th January 2015 an advance agreement was made in 100 rupees stamp paper as per the law in respect sale of 86 cents of land.this 86 cents are belonging to 12 members of family, since these members are residing different places this document has been send to these members for signing the document.after signed by all the members it reached back on 10 march 2015. The purchaser of land gave the advance of rupees 10 lakh on the next day.the time period for registration of land is given for 4months. On 11 july 2015 the purchaser came and said that they are ready for registration on 25 august 2015. They argued that 4month period should be consider from 11 March 2015(the day on which the advance amount given).some supporting documents for registration was also not ready like location certificate. 5 members from us asked for compensation. There were not ready for that and asked that if we are not ready for the registration they are likely to cancel the deal and the advance money to be return back. Those 5 members asked for compensation was not ready to return back their shares,but remaining 7 are ready to give back. What will be the court decision in this issue if they went through legally?