This grows your list. It will merge duplicate contacts. It will never delete.
“Replace Contacts on this List with only Contacts in File”
Only the contacts from the .csv you are importing will be housed in the list.
Click “Import”
Click okay on the dialogue box
“The upload was successful. An email will be sent to the specified address once your import is complete.”
Wait for upload email notification.
NOTE: If you did not enter an email address (step 4L) you will not receive an email. You will have to come directly back to the Lists tab (step 4e) and view your group.