Assign Contacts: Set the Registrant, Admin, Technical, and Billing contacts for a specific domain using existing contact IDs. Executing this will result in a synchronous update at the registrar.

Endpoint: POST /{id}/assign-contact

Parameters:

• registrant (required, string): The Contact ID (from List Contacts) to assign as the primary owner.
• admin (optional, string): Admin contact ID. Defaults to registrant if omitted.
• technical (optional, string): Technical contact ID. Defaults to registrant if omitted.
• billing (optional, string): Billing contact ID. Defaults to registrant if omitted.