How to associate a DCS contact with a Fusion contact?

Summary:

Associate a DCS contact with a Fusion contact

Content (required):

We know that using the Digital Customer Service (DCS), it is possible to create a Contact to access the DCS, through selfRegistration.

However, when our user informs a CPF on the Sign-up page, the DCS system must check if this CPF already exists in a Contact and if it exists, just link this DCS contact to the Fusion Contact.

Today DCS creates a Contact by linking it to an Account, and what we need is to associate a Contact that comes from DCS with a Contact that already exists in Fusion.