Herrasing to repay money by a private money lendor

Contact local advocate and issue him notice that you are in no way responsible and still he has been using threats and subjecting you to intimidation, and inform him that he can approach the court for proper remedy and warn him that any further visits or intimidations will be taken seriously and the matter has to be reported to Police.   After that if still the person harasses, with the help of your advocate file complaint and enclose the copy of notices.  Use recording devices freely and collect CCTV footages if any if the intimidation is in public places.  That cheque or such documents were hopelessly barred by limitation and can never be enforced.  Do not commit anything.  You may be spending few hundreds for issuing effective legal notice, but it saves you from harassment  but ensures mental peace and protection to the family.

You have only intimated his advancement and never stated your reply to him when he approached you.

One can not state validity without looking into them and without knowing facts.  The simple issue here is whether you are involved and can be subjected to intimidation by the third party or not.  If the documents are valid, he might have issued atleast a notice demanding such payments.  Cross the bridge only when it comes, and it gives suspicions to the readers about the integrity of your father and his yielding to such pressures.   No one can provide guidance on mere assumptions.