SharePoint 2010 item permissions workflow - getting user from look-up list

On SharePoint Online I have a 2010 workflow with an Impersonation Step to Replace permissions of the current item so only the person who created it and also the Administrator for the corresponding region can see it.

Presently the Administrator is hard-coded in the workflow, looking up from the main company directory on Exchange.

The Region is a choice column on the list the workflow is running on.

Whenever a regional Admin changes - or additional ones are added - the workflow will need to be adjusted so the permissions are changed (person removed or new ones added).

My question is: **How would I use a Lookup list** with Region and the corresponding Admin so the workflow can look at that instead of the names being hard-coded on the w/f? This will be a better interface, so the admin team can change admin roles from a list themselves rather than having IT to change the workflow each time.

Thanks!