If you have the Advanced Portal activated and you have selected Manage Contacts from the list of options, your constituents can use the portal to see a list of all their contacts and add new ones.
For companies, they can manage their company contacts and identify the Primary 1, Primary 2, Invoice, and Inactive company contacts. This information will update their profile page. If they add any contacts, they will also become constituents in the database with an employer-employee relationship with the company.