In this case how the Buyer is in Heavy risk, Since Buyer is giving the Post dated Cheque with Contract agreement (Mentions the Token Advance + Post dated Cheque) and Notarized. Till the actual sale deed is not happen the Seller can't realize the Cheque considering the future date.
Didn't get the point what you want to safeguard from Buyer's perspective.
In your previous post you have mentioned to give cash advance or token advance which is not post dated in addition to post dated cheque.
If the sale process did not happen how to get that money back ?
I agree with you on the post dated cheque it cannot be realized until that date.