You can add messages to a message set by importing IBM supplied messages using the New Message Definition File wizard.
Each IBM supplied message you import results in one or more new message definition file within the message set. A new message definition file is created for each namespace defined for the message set. The name of the message definition file defaults to the name of the IBM supplied message, but the New Message Definition File wizard will allow you to choose a different file name.
When you import using the New Message Definition File wizard, you can only specify one IBM supplied message definition for each import operation.
If the message definition file already exists, you must have permitted overwriting to occur for the import to proceed, in which case the existing content is deleted and recreated.
A report file is generated during the import operation which will allow you to examine what occurred during the import process and check any errors that could have resulted.