A program to copy the spotlight images and save them to a local folder. This can be set as a Task Schedule which will run daily etc.
Download the program from the releases page, and run the installer.
Upon running the program the first time, a locations.txt file will be created in C:\Users\{your_username_here}\AppData\Roaming\Grab Windows 10 Lock Screen Pictures. This file will contain the current username.
To add usernames to grab images for, open the locations.txt file and add usernames one per line.
The images are saved to C:\Users\{username}\Pictures\Spotlight Images using the first username in the text file. To save to a different user, change the order of the usernames. To change the save location within the user's folder; can only be done by editing the program.cs file directly.