Mandate approvers to edit fields in a service request

I'm trying to build a couple of service request templates. I have it like I want it except for one thing.

Each template have 4 levels of approval assigned to specific organizational roles.

These approvers must be able to edit a specific field in the template in order to give the necessary info to the technician.

Im thinking about using the "EDITOR" field and using field and form rules to auto assign all 4 approvers to "EDITOR" and simply having triggers with each approval level to mandate the field the approver needs to fill with information. But I dont know how to do it properly. However, the "EDITOR" field isnt editable by anyone but the requester while filling out the request. And when trying to use Field and Form rules the "EDITOR" field doesnt show at all, so I have no idea how to do it.

Is it even possible?