SQL Server AlwaysON : start sync with secondary for selected databases I have an SQL Server 2012 AlwaysON cluster composed of : 

win-mssql1 : witness file share

win-mssql2 (INSTANCE 1) : primary server

win-mssql3 (INSTANCE 2) : secondary server

Recently I had the host "win-mssql4 (INSTANCE 3)" as a new secondary replica. My goal is to :


Manually synchronise a huge database (let's call it "BaseSyncManual") with this new server.
2.Later, synchronize the other databases which are in the AG.


To do the first step, I have used the followings commands :

On primary server : 

BACKUP DATABASE BaseSyncManual TO DISK = 'I:\MSSQL\MSSQL12.MSSQLSERVER\MSSQL\Backup\setra_full.bak';
BACKUP log BaseSyncManual TO DISK = 'I:\MSSQL\MSSQL12.MSSQLSERVER\MSSQL\Backup\setra_log_2.trn';


On secondary server :

  RESTORE DATABASE BaseSyncManual FROM DISK = 'I:\MSSQL\MSSQL12.MSSQLSERVER\MSSQL\Backup\setra_full.bak'
    WITH NORECOVERY

    RESTORE DATABASE BaseSyncManual FROM DISK = 'I:\MSSQL\MSSQL12.MSSQLSERVER\MSSQL\Backup\setra_log_2.trn'
    WITH NORECOVERY


On primary : start the wizard to add a replica and choose "skip initial data synchronisation"

On secondary : alter database BaseSyncManual set hadr availability group = AvailabilityGroup1;

Everything runs fine and the result is what I have expected :



Now I want to re-run the "add a new replica assistant" in order to synchronize the remaining databases (Base1,Base2,BaseSyncAuto) with the "full" parameter (automatically backup restore and join to AG). But there is no way to do that ! the replica as already been added to the AvailabilityGroup : 



and I can't Add a database using "add database" because they are already member of the AvailabilityGroup on the fist secondary replicate :



What are my options to sync those databases with my new secondary replica ? Am I condemned to do it with manual backup-restore-join to AG ?
Yes, you will need to manually backup and restore the databases, with logs, to the new secondary and then join the databases to the AG.  This might help.