Unable to access Business Registries party endpoint

@Melissa Can you clarify how one would link a business to an account as you described above?

We are required to use our premium account (as software developers) to perform filings for numerous legal firms. Say that a firm needs to perform a change of directors filing for a BC company. In the existing system we compare the directors online with those in the firm’s records to ensure that we are in sync before proceeding. Would we somehow need to have that BC company associated with our account, or otherwise for that firm to both obtain the director info and submit the filing? If so, what is the process for that association? In the existing system we can perform filings by having the firms provide the company password or a filing code that may have been provided for an annual filing.