@TereseToth_NPS If I understood correctly, you want assignments that are copied to a different course to be in the same Assignment Group that is in the parent course. This may depend on what you are selecting to import. 

There is information on this linked here What is the Course Import Tool? - Instructure Community - 21

In my experience if the assignments are being imported individually, they are placed into the imported group and the individual teacher of the course will have to move it to the assignment group they would like it in.

Based on the guide listed above it states. When selecting assignments only, Canvas imports all assessment items within the Assignments page (including any associated quizzes and discussions). Assignments will remain in their assignment groups if an entire assignment group or all assignments are imported.