The feature "Watch for new images" in the Slide Show Options is exactly what I was looking for, but for me it only works if there are images in a single folder.
If I use a folder with images in different subfolders then the slide show will not update if i add images in any of the subfolders.
Would be great if that would work anytime in the future, because i'd really need that future at my wedding in 3 month

Best regards
yeti5