Pre-Filled Input Value - More Options to Link to

At the moment the Pre-filled input value only give you limited options to link to another field. It only allows you to add default fields for the logged in user and not for a different Data Search for All Users or Agents. In our organisation tickets are not always logged by the person who is logged into the portal. Often Admins or Supervisors log tickets on behalf of someone else who knows what access each person needs who is entering into their team. This leaves the pre-filled input value option almost unusable as it will import the incorrect information based on the person logging into the system rather than who the ticket is actually for and does not show custom fields in the options to select e.g. we have payroll number in our agent and requesters but these fields do not show up.