A while back, I requested, and Kovid added the option in 'Add by ISBN' to auto-(adds to other allowed) tag: I use <In paper Library>. (976 entries of which I now have 624 in e-form)
I add small batches (10-15 books) so I can check for 'failed to add's ' (some of my books are so old, the ISBN is not found, listed or did not have one. ever) and fix or set aside for later resolution.
A (USB-keyboard wedge) barcode scanner is a boon to this task as I suspect MR folk have more than 1 bookcase