Only your VoIP elements can be configured in a Leader/Follower configuation - Signaling Servers, and Media Cards.
Your Option 11 cabinets are all controlled by a single SSC card in the Main cabinet.
It is possible to convert any/all of your expansion cabinets to survivable cabinets. Survivable cabinets become standalone systems if the link to the SSC card in the Main cabinet is lost. Functionality is limited when in survivable mode. Generally you will not have access to voice mail, and the digital/analog phones in each survivable cabinet can only utilize trunks contained locally in the same cabinet.
There is a lot of downtime when a cabinet either enters survivable mode, or exits from survivable mode as well. The SSC card in the survivable cabinet reboots in case of a state change, after a watchdog timer expires.