breach of written agreement to make more money

dear all,

my sister in law was recently invoved in a car accident where she knocked into my neighbour's car and injured an old lady. She paid for the repair and I got the other party to sign an agreement later, not to claim against my sister in law's insurance.

however, much to our surprise, the neigbour went on to pursue a claim with the insurance company.

I wonder if there is anything I can do about this. Please advise

That agreement is useless because asking people not to report an accident is against the law and any agreement that has illegalities in it is automatically null and void.

For example if you signed an agreement saying that you will rob a bank next year, that agreement is void.