Once you have placed a server in a pool, it is shown as a pool member in the Resources pane, for example:
When you add a server to a pool, XenCenter will attempt to resolve any pool configuration issues if possible:
If you add a free XenServer to a pool whose master is licensed (with Advanced, Enterprise, or Platinum), you are prompted to upgrade the joining server's license to match the master's license. You have to do this to add the server to the pool. If there are no licenses available, you cannot add the server to the pool.
After joining the pool, you can change the license of any pool members. The server with the lowest license determines the features available to all members in the pool. See Managing licenses for more information about licensing.
Note that there may be other hardware or configuration issues that will prevent a server from successfully joining a pool: see Pool requirements for details of resource pool prerequisites.
When a new server joins a pool, the pool master's networking configuration, including network and bond information, is automatically inherited by the joining server. However, the joining server's management interface will not be changed to match the master, so you will need to reconfigure it after joining in order to use the same bond as the pool master. See To change the management interface for information on how to do this.