I believe some companions (NV Willow?) have a special container that holds items common to all outfits. Depending on whether the container has priority over others, such items might be permanent, i.e., the character always wears those items regardless of the selected outfit. If outfit containers have priority over the special container, then items in the special would appear only if a particular outfit had no matching item for that slot. I don't think Brisa was coded with a special container, but if not it should be possible to do so, with a lot of effort.
Edited by grneely, 21 February 2015 - 05:32 AM.