Add optician drop down to invoice

[drbvec]

I want to track some items better like individual capture rates for my opticians.  But when the patient does not purchase glasses they get checked out by the front desk staff, so the front desk staff's name is on the invoice and not the optician.  As I still want to be able to know who checked a patient out separately, can we add a Optician drop down box to the Physician and Staff dropdowns?  Also, can this dropdown for optician be auto-populated from the order screen if there is one pulling into the invoice?  Thanks.