Sign in with your Brand Registry username and password.
Click on "Help" in the upper right corner.
Under the "Enrollment and Setup" section, click on "Brand Registry Roles".
Scroll down and click on "Contact us".
On the left side, expand the "Update Your Brand Profile" section.
Click "Update Role or Add New User to Account".
Fill out the form that should be displayed on the right-hand side.
It should look like this:
Name: KD Global Distribution LLC
Marketplace: Amazon.com
Role: Add Administrator and Rights Owner.