@Rajesh11735 from the link you provided.....
Authenticating and Authorizating users using the Local Database
Note: In order to authenticate users against the local database on the router, EAP needs to be used. However, in order to use EAP, the local ...
@michael18 then you'll have to use a policy based VPN. You can define a backup peer IP address.
https://www.cisco.com/c/en/us/td/docs/security/firepower/70/configuration/guide/fpmc-config-guide-v70/firepower_threat_defense_site_to_site_vpns.html
@jmaxwellUSAF you'd see that command if you made any changes on the standby appliance. You should ensure you make all changes on the primary ASA only.
If you wish to test synchronisation is still working ok, make an innocuous change from the primary ...