Crosslisting in Bb Learn is different than the Bb Vista model. In Vista a parent section is set against ALL child sections that contains the content for the course. The child sections are populated with enrollments and crosslisted with the parent. Instructors are enrolled at the parent section and can then administer the sections from one location and see all enrollments for all sections within that parent. Students would only see the students enrolled in their particular section.
In Bb Learn however, crosslisting is more of an enrollment Merge where all the enrollments from the various sections are merged with a parent section and all students can see all students regardless of section.
Until the Integration Framework is implemented this Merge is done via the UI. Framework Integration allows for the use of a master_course_key element, this is populated with the external_course_key of the course intended to be used as the primary course to merge enrollments to.
Bb Learn Structure/Setup
One known issue with Merge is if a user is enrolled in the parent section, disabled and then enrolled in a child section, the parent section enrollment status overrides the child enrollment status. For this reason it is recommended that a master course is created and all specific sections get merged into this "master". For example, rather than having three sections, sec01, sect02 and sect03, and merging section enrollments from sect02 and sect03 into sect01, create a mastersection01 course and merge all three into that.