Thank you JessT for the quick response. Yes, I created a backup before making any changes, always have and always will. But as I mentioned, the inventory was entered into QBDT as non-inventory from the very beginning of using POS years ago (the items come over in the financial exchange with POS). 

If I deactivate all my items and create new ones in QBDT as you say - will I then have twice the amount of items (even if half of them are "inactive")? I'd really prefer to not have double entries of everything.

Could I essentially just transfer everything Except inventory over to QBO when I begin? Then, create an Excel sheet of inventory and import it into QBO? How would that effect financials?
Thank you!