1. If you’re using Lightning Experience, from the campaign members related list, selectImport Leads and Contacts. If you’re using Salesforce Classic, from the campaign detail page, select Manage Members | Add Members - Import File.The Data Import Wizard appears.
2. Select Accounts and Contacts, then select Update existing records.
3. Set Match Contact by to Salesforce.comID.
4. Set Match Account by to Salesforce.comID.
5. Select the CSV file that contains your import data, andclick Next.
6. Map column headers from your CSV file to thesefields.Account: Salesforce IDContact: Salesforce IDContact: Last Name
7. Account: Salesforce ID
8. Contact: Salesforce ID
9. Contact: Last Name
10. Click Next.
11. Review the import settings, and then click Start Import.