Since transmitter power and terrain features limit the range of radios, information will sometimes be relayed from one station to another until it reaches the intended party. For example, the Civil Air Patrol may relay information back and forth between a team in a remote canyon and incident base. Any information added by the relaying station should be identified as such. This procedure is necessary to make sure the message maintains its original meaning from sender to recipient. Small changes in a relayed message may, after a few iterations, end up totally changing the meaning of the message.
Similar agencies control radio transmissions in other countries.
All radio frequency users must have a license to transmit on that frequency, issued by the FCC or appropriate governing agency. A search itself is generally not considered to be a life or death emergency, and frequencies used by incident command are used under an FCC-issued license. As a non-licensed SAR person, it is OK for you to use the frequencies designated by incident command for search information only, and only during the duration of the mission. Only licensed amateur radio operators may use frequencies other than the mission frequency, unless a life or death emergency exists. The FCC requires that frequency users identify themselves using their FCC-issued call sign at least every 30 minutes.