Ability To Allow an Entire Block of Information to be Extra Card Detail

I would like to be able to add more information as Extra Card Detail, sometimes pulling from other topics (e.g. via a portal) without having to reference them in a rem that is directly a child rem of the parent (which is not exactly the right way to use references imo, and could create some clutter).
Additionally, as of now, if a rem is a grandchild rem of the parent rem and tagged with ##ExtraCardDetail, it isn’t included as Extra Card Detail of the parent rem (understandable, because the condition is that the rem must be: a. a child rem of the parent rem + b. not a card item).
It is possible, though, that that is the only right way to structure the information.

It would be nice if we were not limited by these conditions and could instead insert an entire block of information as extra card detail.

A familiar way to do this, in theory, would be if this tag could be transformed into a template, wherein there is a slot attached to the tag. This slot can then be filled in as you would a regular rem, and the entire content of this slot would appear as Extra Card Detail.

Here’s what this would look like:

To clarify, here, everything that is a descendant of the slot Extra Card Detail, would be included as Extra Card Detail.