We use UID to uniquely identify a Client or Contact.
You can make the following links in an import file or even across import files as long as your UID is unique:
- Client to Client
- Contact to Client
- Contact to Contact
In all cases, you set the RelatedToID of one of the linked Clients/Contacts to the UID of the Client/Contact you want to link it to.
You can also set a name for the relationship in the RelationshipType column.