Sending reminder notification to designated approvers who have not responded

Hello.  I need to know whether I can set up reminders in the email for a workflow task (I used assign flexi task)  so that only designated approvers whose response is outstanding will receive the reminder email.  In the Review CMC workflow, I individually select approvers for each list item submitted.  I did not create a group and name them approvers due to the fact that certain task (list item) will require different approvers.  In the Approvers Review and Action workflow, they have the option to reject or approve the request.  If only 1 of 4 required approvers are outstanding, how do I make sure that only the outstanding approvers gets the reminder notification email when all other approvers have responded?  Will the reminder go to all individuals listed as an approver even though I did not designate them as a group in the previous workflow?  I have attached all 3 stages of the workflow that push drive this process for your review.