Summary note, possible to add Excerpt?

After making a summary note of multiple notes, would it be possible to add content to it? other than just comments?

For example, one would excerpt multiple assumptions in a model as separate notes and then use the summary feature to connect the model specification which meets all those assumption (so for example an excerpted formula from a slide etc.).

Or even better, to just treat it like a normal note with all the features one might expect!
Such adding children to it, using it as a container and adding excerpts to it.