"because both employers are non-profits"

Off them this type of option as an example: The clerk also mows the lawn on the weekend. They submit a bill for the labor and show its value, adding a 100% discount. Now the NFP has proof of the value for donation support and the person would not get a 1099-NEC. They also would not get the money 🙂

And don't ever let worker comp insurance audit these people. Nothing like trying to explain why the clerk hurt his back mowing, when that isn't his job rating.