Dressing extras appropriately for a scene

When I try to make my own movies, it's frustrating that most extras in the scene I'm shooting wear inappropriate outfits for the setting: a war movie will have people in casual civilian outfits on the battlefield, or a scene in a hospital won't include doctors and nurses in the background. The game allows a maximum of three leading roles (named characters whose costumes I can select). Is there any way I can solve this without auto-animated props? I'd use those, but (a) I can't design my own; and (b) when I install auto-animated extras, they tend to overwrite my studio ornaments for some odd reason.

in a movie making you can drag your extra onto the clothes hanger and it will let you change there outfit.