Personalization of a form

I have a personalization to be done on the "Enter and Maintain Contingent Workers" form invoked through the PRJ Admin Responsibility. Enter and Maintain Contingent Workers" form invoked through the PRJ Admin Responsibility. I need to add a filter so that the form does not show records of Person Type = Contact Currently the tree view does not show the Persons of Type "Employee" . So, I am assuming that condition must be somewhere. If I can find that condition, then I could add in mine as well. Can anyone be able to tell me how to go about doing this ? Thanks Leonard