Once a copy node is running, you can assign a new parent to it by using the ALTER MIRROR SERVER statement on the root database server:

ALTER MIRROR SERVER "copy-server-name"
 FROM SERVER "new-parent-name";

The statement is recorded in the transaction log on the root database server. When the change is pushed to the copy node, the node recognizes that its own definition is being altered, and then connects to the new parent that is specified in the statement.

 See also