Note: You must be an "Account Manager" user in ProviderSuite to perform this task. If you do not have access to the Setup tab in the ProviderSuite, please forward these instructions to another user with Account Manager permissions.
Go to the Setting tab for the Account to which you want to link an existing user
Click on Users Sub Tab
Click on "Link Additional Users" (left side of the screen)
Search for the user by their last name (last name only)
Find the user that you want to link to the account
Choose security level for user
CC to Manger defaults to Yes
Click on blue "Link User to Account"
The new user is attached to your account