I think they should just add sections. Meaning that u can section them to keep organised. Each section should have no link to each other meaning that if you have a INT. CAFE-NIGHT in one section, you can have another one in each other section too but I also think there should be an overall section where u would put your backgrounds & overlays that get used in more than one story instead of uploading them again (:
You should also be able to move backgrounds & overlays out of one section and into another (:
Edit = I’ve only just realised this comment pretty much just adds detail to your idea @IrisLevont 