Keep a written record of the incident and all traffic passed. This does not mean a copy of all formal traffic. Simply an overview of the message. Make ALL instructions clear and concise, using as few words as possible. Use tactical call signs.
Different nets handle different traffic.
Should someone try to pass traffic that should be on another net, refer them to the correct net. There are two types of NCS backups. The second type is a person that maintains a duplicate log of everything happening at the event and is available should there be a failure at the primary NCS location. Whenever there are enough people working an event, an offsite backup NCS should be maintained. This person must be operating with the knowledge and consent of the NCS station and should be known to the entire net.