Make it easy for a Consumer who wants one to communicate through an Advocate. Tell the Consumer that an Advocate has no power to act for the Consumer and gets no access to their information except when the Consumer is present and consents. An Advocate may be presumed to have no authority to set up or change an account unless also an Authorised Representative.
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.