It is possible to move users from one KS account to another.
Go to the Accounts > Move Users page and use the check boxes to select the user(s) you wish to move.
Click Continue to move to step two.
Use the radio buttons to select the new destination account for your user(s).
Click Move to account to register your changes. You will see a popup box advising you that your user(s) successfully moved to the new account.