If it's the case that you want to index some data locally and forward other data to another indexer, then you want to route the data using the instructions here.
Alternatively, you can just index the data on your local instance as well as your remote instance, by specifying your custom index in the appropriate index in inputs.conf and then using indexAndForward = true in outputs.conf.
Whatever your requirements are, there will likely be some data-routing work involved if you want to have different data available in different instances.
A much simpler alternative is just put your data into a custom index on your main indexer, and then restrict the relevant users to only having search privileges on that index. You can then provide access locally on that instance, or use a remote instance to distribute searches
... View more