I did something similar a few years ago for a project. In my case, I have one psychiatric practice that has multiple psychiatrists that work in that one office. But there are only 2 secretaries that handle things for all of the providers. Although in my case, it was client records that needed to be edited - same principle can still be applied, I think.
Example - profile edit page.
Create a membership called secretary - this will allow you to use the page access controls to designate which pages, blocks/forms the secretary can access.
Create a new profile edit page with form that the secretary can access - be sure to add a dropdown select field that lists the members that the secretary has been assigned to. This allows a secretary to modify info for multiple members. As an example - a dentists office that has one secretary that handles things for 2 different dentists. Secretary can update profile for either dentist.
Upon selecting member and submitting form, the appropriate profile should be edited - provided your sql statements are correct.
This is just a quick explaination. We can get into specifics if need be.