Google drive server saving images only in field user's gdrive, not the one with server


I am testing Google Drive as the server for ODK. I have created a form and shared its xml file with field staff via google drive sharing link, sending to their gdrive accounts. The data submission URL target file is in my drive. The setup is working fine, but only for the data. The images, I discovered, are actually being stored on the user's own gdrive, with my data file only having a URL to the images in user's gdrive.

I am facing 2 problems here. First is that I cannot take a backup of the whole data, since images are not in my gdrive folder. Secondly, it seems to be a data risk in the situation if the field user stops the share access of his gdrive folder containing images (or his account is suspended, or any other thing), because only he will have the image file, not the central server.

Let me know if my observations are correct, and any remedy to fix this.