Please forgive me...I do not mean to take over this thread but if the guns are inherited why would you need to report them?
He wants to be legal. He's in New Jersey. NJ has some of the most godawful, onerous, harassing firearms laws in the country. When I in high school, I was at the Jersey shore and went to a 5&10 and asked to see an air rifle. The clerk asked for my NJ-FOID. I couldn't even touch it without a FOID card. That was 30 years ago and it hasn't gotten better. I don't even try to pretend to understand NJ gun laws, I just avoid ever crossing the Delaware to that state of gunowner misery. Contact a NJ lawyer and see if you're already a criminal for merely possessing guns that you didn't go through the permit process to acquire. Remember, Pennsylvania is only about 70 miles from anywhere in the state if you need to sell them to a dealer to avoid forfeiture.
Good luck to you.