Originally Posted by Ripplinger
If it were my library that I was giving total access to other family members, I would give them access to a duplicate copy of my library only. Anytime I made a change to my library, I'd use a batch file to recopy the real library over to the duped one that others use. Since ebooks are so small, it shouldn't cause any space issues, but would give you total peace of mind about their accidentally editing something.
I agree that this is the totally bulletproof solution, but it does add a level of complexity and hurdle that I'd rather avoid... Caliber being very slow on extractions and not too good at synchronizing libraries, a fresh copy of the "user" library would have to be made each time something was changed or added.
My preference still goes to an option that would block editing / deleting altogether.