Is it possible to add executive assistant to Approval Workflow

We have a requirement to add executive assistant to Approval Workflow for some of our executives. However, our approval rules are currently set at job level and there is not a way to insert the executive assistant is employee/manager hierarchy. Does anyone have any ideas on how to possibly go about doing this? Issue is that the top executive could have different level reporting directly to them so we can't say at this level stop and then do individual approvers for executive assistant and the top executive.