BM3 ReCycle BiN!
Recycle Bin, for:
... and what ever else might need retrieving.
The user is in full control of emptying and restoring etc. So if it fills their iOS storage, that’s their choice.
The Bin could have a restore for the files, or you could move them around BM3 manually (you may not want to put them back to where they originally came from).
Everything! deleted should go to the Recycle-Bin as default.