Agreement to sell cancellation and how to resell

Dear Sir, My father has entered into an agreement to sell in 2006 for a residential plot. Total sale amount 35 lac out of which that 5 lac amount is paid as token amount (biana) and 30 lac to be paid after three month as buyer take 3 month time to execute the agreement and to pay the balance 90% sale amount. I (daughter) have signed as witness in that agreement. • Now Mr Tarun who is the buyer paid biana in 1,june 2006 of 5 lac through cheque and agree to pay the balance after three month.But on 18,June 2006 he approach my father that he unable to arrange the balance amount so he want to execute a fresh agreement to sell in name of his relative Mr Davinder as he is the actual buyer so my father agree and cancel the previous agreement between my father and mr tarun and made a new agreement to sell in 1,July 2006 between my father and mr Davinder with the same terms and condition mention above. And my father make them clear that he cannot give any more grace time after three month as he need money for an urgent family need and the buyer agree. • Now in Oct 2006 after three month period they again approach my father that they need more time as they could not arrange the amount my father already made them clear earlier that he need money for his certain obligation and cannot give more time but after some heated discussion my father gave them 1 month grace with interest 6% to arrange the balance amount and made clear that he will forfeit the biana as per clause of agreement to sell if again they unable to arrange the balance payment .But all this arrangement (grace period and interest)happen orally nothing in written (verbal agreement agreed mutually). • Now again after expire of one month grace period they could not arrange the full amount and offer part payment i.e 18 lac and remaining balance after one month with interest 2%.My father gets very angry this time and refuses to enter in such arrangement. The argument turn ugly and my father told them to leave by finally putting condition that either pay the full remaining amount in one shot with 9% interest within 10 days otherwise the biana is forfeited as per sale agreement.(everything orally i.e about time and interest said verbally nothing in written). • When my father enquires about Mr Davinder the buyer he came to know that the address he mention in the agreement is false he never reside there. But any way after 15 days they send some mediator Mr Ashok to talk on the matter my father doesn’t know him so he refuse to talk and said Mr Davinder the buyer should approach he will not entertain anyone else but Mr. Davinder never turn up and my father also rest the matter and forfeit the baina . Now my questions are: 1 Does my father rightly forfeited the biana(token amount 5lac) as per condition of our agreement ? 2 As from 2006 till today 2014 they never turn up so now if my father again wants to sell his property does the previous buyer Mr Davinder has any claim or brings any implications? 3 My father does not register the cancellation of the agreement to sell (As its conditions are not fulfilled by buyer and moreover the agreement contain the clause clearly stating that if the amount is not paid within 3 month the agreement stand cancel and the biana(token amount) is forfeited which is dully signed by the buyer) Does the cancellation required? My father is 75+and suffering from major asthma so he wants to sell this property as he does not handle any botheration now. Please provide your expert advice on the above matter. Thanks