I understad that I can add both Catalysts to MARS and that I can add primary FWSM as a module to primary catalyst as well. But how can I add secondary FWSM.
Any ideas appreciated
If you have already configured the primary, you don't have to configure the secondary. No need to configure the secondary as it is not recommended to do so, In case of a failover the secondary firewall will automatically take over the active configuration( EX: IP address) of the primary so the source of the syslogs will remain the same