You can move files into a folder without it being open. I opened a
flash drive and my pictures folder with two test folders in two separate
windows in Windows Explorer and was able to drag images from the flash
drive to the folder.
The problem here is that once I drop the file, the folder opens to
show the contents. So I’d need to open up multiple instances of File
Explorer. One for the flash drive and one for each folder I want to drop
to. The solution is a simple one. Instead of dragging the images into
the folders contained in various windows I’ve opened in File Explorer, I
can open the flash drive in file explorer and then drop the images
using the file tree on the left side. Since the files I want are under
Pictures, I click the chevron next to Pictures.
Hope that helps.