A CS18 can be thought of as essentially a hardware version of the UC Surface software control client, but with Audio I/O capabilities. But, because the AVB audio stream routing between the CS18 and RM is negotiated automatically when you connect a CS18 to an RM, there's no way to control or predict what happens when a second CS18 attempts to make an AVB connection to the RM. Because it's not currently user assignable and not predictable, using more than one CS18 is not currently supported. But...
Though more than one CS18 is not currently supported, it is possible to use more than one CS18 per mixer, provided that no more than one of the CS18's has an AVB connection to the mixer.
This mean only one of the CS18's will be able to utilize the local audio I/O features with the RM (when it and the RM are connected to an AVB switch). The second and third CS18's should be connected to a non-AVB switch or directly to your router, so that they can't make an AVB audio connection, and will only make the control connection. If you don't need the local audio I/O on any of the three CS18's, it's not necessary to have any of them on an AVB switch.
