An agreement is what is agreed to between two or more parties. A unilateral modification by one party to the agreement, made subsequent to the execution of the agreement, does not bind the other party. What is binding is only what has been agreed to by both the parties. You have also mentioned that the second party and the witnesses have not put their signatures to certify the handwritten changes made to the initially agreed MOU. So, the modification will be invalid and of no effect in law.
Secondly, if this subsequent modification has been made with a dishonest or fraudulent intention with intent to cause damage or injury, to the public or to any person, or to support any claim or title, or to cause any person to part with property (as is described in Sections 463 and 464 of IPC), then such modification to a previously existing MOU may even amount to the offence of forgery. Depending upon details facts of your case, i.e., if such dishonest intention is also clear, you may file a complaint with the police or the court, as the case may be.
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