Setup a Wallpaper Slideshow including Subfolders in Windows 10

Solution
Open the parent folder that has the subfolders containing images.
Click on the search box, and type the following search query:

kind:=picture

Another Windows Specical… I did not check the build Version but in some cases you will have use this search query:

art:=picture

Select all or the image files you want from the search results, right-click and select Set as desktop background.

That’s it!