Business / Directory profiles in the Directory tool supports the ability to add multiple contacts, each with their own permissions.
To add an additional business contact follow these steps:
Login to the Control Panel
Go to the Directory
Find the directory profile you want to add the contact to and go to the menu
Click on Add Business Contacts to add a new contact
You can then set the permissions, the contact type and assign them to the CRM record (if they are not in the CRM, you will need to add first)
Keep in mind the main contact should be set by editing the directory profile.