When a cluster of Strategy Intelligence Servers connects to Strategy Web, the following behavior can be observed in the Strategy Web Administrator page:

All Strategy Intelligence Servers in the cluster will be added as a single unit, as shown with the example above. If only a single Strategy Intelligence Server is added, then it means that the cluster has possibly been broken because it is not possible to add a single node from a cluster without adding the other nodes as well.
It should be noted that the properties of each Strategy Intelligence Server will be set independently of the cluster. This can be beneficial if the Administrator would like to set the Load Balance for one or more Nodes to zero and use those machines to run Schedules and Strategy Narrowcast Server services only. Therefore, if it is desirable to make a change to the properties of all nodes in the cluster then the properties will need to be modified for each node in the cluster.