"Allow assignment selection at absence entry" and Advanced entries for Admin only

Summary:

Due to multiple limits of advanced entries we would like to enable assignment selection for Sickness absences.
Since the organisation is large, many issues would arise if Managers were able to select assignments for Sickness absences.

Is it possible to enable assignment selection for Admin only?
Or if that is not possible, is it possible to enable assignment selection but add an error to prevent absence creation or changes if the user is not an admin?

If either of the former are possible is the same possible for advanced entries?

We would like managers to only be able to enter Basic absences on all active assignments and HR/Payroll teams to manage any valid cases where not all assignments should be on the Sickness absence.