Will it ever be possible to import a QTI with additional items into an existing, already populated Item Bank?

Again, this assumes the bank already has items, not a newly-created, empty bank.

Also, I have found that even a bank that I empty by deleting all items cannot take items from a direct import. Although the import process will again become available and goes through the motions of a successful import, once I get the successful import message, my bank is still empty.