Originally Posted by macropod

Word does not support having more than one referencing system in the same document. Nor can you change the way Word formats a particular reference Style vis-a-viz parentheses vs braces vs brackets, etc. The only editing options are those offered by right-clicking on a given citation, coosing 'edit citation, then adding page #s and checking/unchecking the various checkboxes there.

The simplest thing you can do to aid visibility is to go to File|Options|Advanced>Show Document Content>Field Shading, and there choose Always.