Thanks @Damian Andre and @dude I’ll review your options!
Can you use “clone_subclient_template.xml” to clone to a different backupSet on the same client/agent? In the parent element “subClientProperties/subClientEntity” there is only a subclientName component.
UPDATE:
It cannot create a subclient in a different backupset, only in the same backupset. Also the content isn’t cloned (eg. virtual machines)
Tried updating the XML like this and passing the arguments: