iPhone Camera Roll and OneDrive

[NWSRG]

Hi folks,

I've managed to set up both his and her iPhones (new model SEs) to upload all pictures to our OneDrive account. There's a Camera Roll folder there, and that all works tickey-boo.

But if I then delete pictures from either phone, they also delete from the Camera Roll. And if I move them from Camera Roll to another folder, and then delete from either phone, they still get deleted from the new location on OneDrive. Maybe naively, I assumed that uploading to OneDrive was the best way to secure them, and the phone storage could then be cleaned as needed?

Is anyone using iPhone to OneDrive backup, who can adivse how I can delete from the phone but keep on OneDrive?

Thanks in advance...and I ask here, as I can't find a clear answer elsewhere.