ChaRM Roles - only specific people appearing in dropdown

Hi everyone

Not sure if this is possible, but thought I'd ask the question

In ChaRM when creating a Change Request or Change Document, you obviously have specific roles to fill out (i.e. Requestor, Developer, Tester etc)

Now, instead of putting in the Business Partner numbers, we would prefer to use the search functionality.  However, we want the search to ONLY pick up people who have that role (or we're able to edit this list so only people appear who we want to appear).

For example, when someone is assigning the Developer they click on the search field and search for ALL. There may be 200 people with BP numbers, however we only one Person A, B and C to appear in the search so ONLY they can be selected. If the person attempts to enter another BP number it would error.

Is this possible or wishful thinking? 

Thanks

Shaun