I have a Course content type which has several "modules." (A module is just a name.) There are also several "units," which may or not belong to a module. A unit has several fields, for example Location, Description.
I have created a Course unit paragraph type, and a Units field in the "course" content type, which references this paragraph type. That way I can create units that belong to the course.
However, I'm not sure how to deal with modules. I could create a Course module paragraph type, but I don't think it would enable me to attach a unit to a module, since there's no way to select an existing paragraph.
Basically I need to create several modules inside a node, then several units, and optionally attach these units to one of the modules I've created.