Can I run 2 CS18ai units with a Cascaded RM32ai and a RM16ai?

I already own a CS18ai an RM32ai and an RM16ai which I cascade using a MOTU AVB and have run quite successfully at a number of gigs recently.

All units are ruing the latest firmware.

I now have the opportunity to buy a second pre owned CS18ai at a very good price from a friend who is moving across to a new 32R, my plan being to position it to the side of the stage and use it as a monitor mix control surface, rather than using a MacBook Pro as I do currently, and to continue to use the other CS18ai as the FOH control surface . I'm wondering if there are any known issues with having a second CS18ai on the network, will there be contention over which of the units provides the audio feed for the talkback and line inputs will I be able to designate which RM unit is the master from either CS18 or from UC Surface without any problems? Any Idea gratefully received!