Cancellation of registry possible?

Hello, my father have purchased a residential property for 11 lakhs. We did it's registry in Jan 2021 and payment method as described in document are mentioned as 5 lac rtgs and 6 lac check of date 28.11.20 At time of registry the cheque was with us only and on a rough paper the agreement was that when he will take all his belongings then we will give his cheque to him. He have taken all his belongings in March and as cheque was old so he requested for another means of payment. However after discussion with him, and advocates in tehsil, it was agreed that as cheque no is mentioned in registry so it's better to change the date of cheque to 28.01.2021 and try to encash. We did a notary of this change in cheque date with mutual agreement and said that of cheque is rejected due to overwrite then we will make payment in other means. Now the cheque is clear and he got payment. We feel alll is okay but some people are saying that he could reject the registration as he has received the money from same cheque but date in cheque is not same as mentioned in registry. This man is bit crook and has got previous criminal history also. Do you think this could be problem for us in any ways. What should be our actions if any to safe guard us. Regards,