I would mount 2 or more separate cloud drive, into a same destination folder or drive letter. It could be even read only drives. I just would upload some files to each drive manualy trough web page or what ever, then i would se those separate files together in the same “virtual” folder .
Now if I want to do it, I got this error message:
“Mount point folder paths are available only on empty folders on basic or dynamic NTFS volumes”