These steps assume you have enabled GTIDs for transactions on the
      sources using gtid_mode=ON,
      created a replication user, ensured that the replica is using
      TABLE based replication applier metadata
      repositories, and provisioned the replica with data from the
      sources if appropriate.
    
      Use CHANGE REPLICATION SOURCE TO to
      configure a replication channel for each source on the replica
      (see Section 19.2.2, “Replication Channels”). The FOR
      CHANNEL clause is used to specify the channel. For
      GTID-based replication, GTID auto-positioning is used to
      synchronize with the source (see
      Section 19.1.3.3, “GTID Auto-Positioning”). The
      SOURCE_AUTO_POSITION option is set to specify
      the use of auto-positioning.
    
      For example, to add source1 and
      source2 as sources to the replica, use the
      mysql client to issue the statement twice on
      the replica, like this:
    
mysql> CHANGE REPLICATION SOURCE TO SOURCE_HOST="source1", SOURCE_USER="ted", \
SOURCE_PASSWORD="password", SOURCE_AUTO_POSITION=1 FOR CHANNEL "source_1";
mysql> CHANGE REPLICATION SOURCE TO SOURCE_HOST="source2", SOURCE_USER="ted", \
SOURCE_PASSWORD="password", SOURCE_AUTO_POSITION=1 FOR CHANNEL "source_2";
      To make the replica replicate only database db1
      from source1, and only database
      db2 from source2, use the
      mysql client to issue the
      CHANGE REPLICATION FILTER statement
      for each channel, like this:
    
mysql> CHANGE REPLICATION FILTER REPLICATE_WILD_DO_TABLE = ('db1.%') FOR CHANNEL "source_1";
mysql> CHANGE REPLICATION FILTER REPLICATE_WILD_DO_TABLE = ('db2.%') FOR CHANNEL "source_2";
      For the full syntax of the CHANGE REPLICATION
      FILTER statement and other available options, see
      Section 15.4.2.1, “CHANGE REPLICATION FILTER Statement”.