The 'Require Control Security' setting is found in the gear in the upper left corner of the TalkShow. Go to the third icon (Accounts) and you will find the checkbox at the bottom.
AirSend (network protocol) supports one destination system at a time. When NDI is released in TriCaster Advanced Edition, you will be able to have multiple TalkShows access the same Network output feed.
today I use a HDMI to SDI + splitter It would be so much simpler if Tricaster mini could return to more then one talkshow on the network. I have heard that a new advanced update is in the works to fix this problem.