You can add additional server connections to a replication rule using the Number of Additional Server Connections field of the replication Add Rule page or the Modify Rule page.
Select the number of additional connections to add for use by the replication/accelerated data copy (ADC) utility operation. You can specify between 0 and 30 additional server connections. Note that these are additional server connections; if the number of additional connections is set to 0, the replication operation will have a single connection. The default is 4 additional connections, along with 12 read-ahead processes.
If the number of additional server connections has been set to non-default and more than zero, then the number of read-ahead processes must also be set to a non-zero value that is appropriate for the specified number of additional server connections.