Message attachments on iPhone
I just cleared up 30GB (!) of my son's iCloud storage that was being used by photos in Messages attachments that were already in Photos - on his Mac, we just dragged the folders into Photos, told it not to import duplicates and disregarded all the misc files it told me it couldn't import.
My question is this: my wife also seems to have a large number of photos duplicated in this way, but she doesn't really use a Mac, only her iPhone, and is averse to logging into her iCloud on my Mac. So is there a way to perform the same operation I did on my Mac but on her iPhone?
A second question is whether there is some way to avoid this duplication of images, a setting that would delete Messages attachments that are already stored elsewhere?
Thanks
MacBook Air 13″, macOS 11.6