MYSQL Group Replication

Question

I have setup a Master-Master-Slave replication where say A B and C, I want to replicate data from A to B (which is working) and B to C (also working) and from A to C which is not working with two masters since one slave is configured to accept only one master.My query is how to configure slave to accept multiple masters.

I want to achieve the following structure :

Tables in Master 1
+--------------+
| Master1-DB   | 
+--------------+
| Table1       |
| Table2       |
| Table5       |
+--------------+

Tables in Master 2 where table 2 is replicated form master 1
+---------------------------+
| Master2-DB                | 
+---------------------------+
| Table1 From Master1       |
| Table3                    |
| Table4                    |
+---------------------------+

Tables in master 3 where table 1 is from Master 1 and table 2 is from Master 2 must be replicated.
+--------------------------+
| Slave-DB                 | 
+--------------------------+
| Table1 From Master1      |
| Table3 From Master2      |
| Table4 From Master2      |
| Table5 From Master1      |
+--------------------------+

Answer 1

You can't configure a MySQL server to connect to multiple masters as a replication slave.

You can configure Master B with log_slave_updates enabled, Master A with binlog_format = ROW and declare table 2 using Engine=BLACKHOLE on Master B, and the replication events from Master A's binary log will cascade through Master B onto Slave C, which would be connected only to Master B (not directly to A).

Otherwise, your alternative is Multi-Source Replication in MariaDB, which (unlike Oracle MySQL) does allow a single server to connect to multiple upstream masters simultaneously, as long as there are no conflicting combinations of schema+table names being replicated. This configuration should work whether the master servers are actually running MariaDB or if they're running MySQL.