Create option in templates to have mirrors detach from external nodes when instantiating

I'll sometimes have mirrored nodes inside of a template which, out of convenience, mirror an external node. This allows for any instantiation of the template to always have up to date information (which gets updated elsewhere). But when I use the template, the new instance is now mirrored to the external node still, where I would instead want it to "copy on instantiate" and detach. I would imagine you could do this with another tag just before the template.

SomeNodeName #detach-mirrors #use-template:cd24d956da18