Business Opportunity Main Representative

When creating a Business Opportunity in APPS10 Enterprise Explorer there is a field “Main Representative”. I want the option to add any IFS user to this but the list of values only allows me to add the names that are listed in a separate screen called “Representative 360”.

However there is only one user in this screen and it looks like a test user. There isn’t any option to add a user (no “plus” icon) How do I make an IFS User a “Representative 360” user?

Thank you.