To limit which paths trigger replication on a particular replication agent on an AEM instance, follow the steps below:
An example where this method is used is when you have one author instance used for two different projects and each project has its own set of publish instances. In this scenario, a replication agent associated to one project will only replicate the content for that project.
The configuration can also be used for flushing specific dispatcher farms. To control which farm gets flushed by the agent you could create a flush agent for each farm then update the replication agent configuration Extended tab with a Host header. For example, Host: www.geometrixx.com.
Make sure to apply the latest Cumulative Fix Pack if you are using AEM 6.2 or 6.3 as there is a known issue related to this feature. See this article for details.