The 'add server' button is a great convenience for users as it lets you easily add multiple nodes to a cluster without having to log into each node's web console, unfortunately many people specify custom data or index paths and this is not possible via this method currently.

What would be great is if you could specify all of the same parameters as you can in the setup screen when using the 'Add Server' button on a node already in the cluster.
I understand that this may not perhaps be possible as you are not technically accessing the node you are adding, but it definitely should be considered if it is feasible.

At the very least we should warn users via the UI that the custom paths set for nodes already in the cluster are not the same for new nodes added.
That way at least they are not expectant that any settings they entered for the original node in the cluster will be replicated to any new nodes that they add to the cluster and that they will have to add the servers via another method or initialise the node via the CLI/REST api.

This has often been a sore point when adding nodes as to change this on nodes already in a cluster, they have to be removed, updated and then re-added, resulting in 2 rebalances, if this was clearer to users then this could be avoided in the first place.

Alternatively being able to have the same functionality in the 'Add Server' button would be much better.