Exploring port-channel configuration on the firewall for redundancy but to my surprise, it not supported on FTD running version 6.3.0-80. require FMC to do it.
looking through the configuration guide version 7.0 state below:
You cannot configure redundant interfaces.
You can only add EtherChannels in FDM on the Firepower 1000 and 2100 series. TheFirepower 4100/9300supports EtherChannels, but you must perform all hardware configuration of EtherChannels in FXOS on the chassis.Firepower 4100/9300EtherChannels appear in the FDMInterfacespage alongside single physical interfaces
This adds Etherchannel in FDM does it refer to the configuration ?