You are creating and configuring a cluster by using the administration console.

All servers that will be part of the cluster must be created before the cluster is created.

You must pick the cluster messaging mode.

Even though you create a non-dynamic cluster, you can change it to a dynamic cluster later.

Once the cluster is created, you cannot change its messaging mode.

The administration console does not provide a way to manually migrate singleton services. It must be set up to be done automatically or by using WLST.