Diagram in Diagram, Diagram as Shape, or 'Imprint' Shape

[0Grit]

draw.io Confluence user here.

When documenting complex architectures I would like to be able to nest sub-system diagrams into other diagrams which contain the sub-systems.

I think I'd prefer being able 'link' view-only external diagrams as a special shape within another diagram.

If it's more feasible, being able to create an 'imprint' or view-only link of a shape that exists within the same diagram would be useful too.

The 'page as a background feature' is useful and was a step towards what I'm looking for.