My attorney did that ISO search and it only showed the one accident. For some reason because of the address change. Now can the insurance find out in any other way?

There are many ways it could come out. If its not in the ISO records, they could still find it. If you end up in litigation, they could subpena your ins co records. They can ask in deposition, or in interrogotories. They may see a reference to the other accident in one of your medical records, employment record, health insurance record, etc. It really depends upon the litigation rules in your jurisdiction, and whether there is any reference to both car accidents in any records. It may not be a big deal if you didnt have much injury in that accident, and you have proof that this slip/fall directly led to the need for surgery. You should talk to your lawyer about this. He/she needs to know. Dont hide it from your atty.

Thank you so much for your help