Q: What are the implications of the setting, "Allow teachers to override the imported roster?"

A: Allowing teachers to override their imported rosters gives them more flexibility to manage their roster.
Teachers can:
  • add students to the class roster, even if they aren't included initially as part of the import
  • remove students if they don't belong in the class, even if they are part of the import
  • move students between roster sections
  • make a student a teacher of the class
  • remove parents from the class roster independent of a teacher
When an import is next run, if the imported roster and the changes that the teacher have made do not line up, the manual changes that the teacher made will stay in place.
However, if a teacher wishes to let the import take control again, the teacher can use the Sync with Source tool under the Manage Roster menu. 

Sync with Source is a wizard that will walk teachers through the process of re-aligning their rosters with the import. It will bring back any students and parents that a teacher has removed, and give teachers a choice as to whether they want to keep or remove manually added students. 
Note: Sync with source does not affect co-teachers.