Hi Greg,
I need some more information in order to properly understand your situation. Can you please elaborate more on what you mean when you say "a different name" instead of one of the one's on the list? Are you looking to add / edit the names on the dropdown choices? If so this can be done by going to the Customization tab under the Users tab link.
How do you identify your Field Service Engineers? Do you assign them to a specific role called "Field Service Engineers"? A tip to point you in the right direction; you can add a field to the Users table and call it ‘UserType’ for instance. Then you can filter the dropdown in the dropdown properties to show Users where ‘UserType’ is equal to ‘Field Services Engineers’ as an example.
Keep me posted and I’ll get back to you.