A library has an Excel sheet that's used as a packing list for books to be loaned to other libraries. Each row represents a single box being packed. The cells of that row have info such as Recipient, Shipment number, Box number, etc.

In one of the columns they'd like to scan the barcoded "Acquisition Number" of each of the several books that will go in that box, such that each scanned number will appear on a new line in that cell.

But when they scan a barcode, Excel moves to the next row, since the scanner is programmed to terminate the scanned data with ENTER.

They cannot reprogram the scanners to remove the ENTER, as they are used for other apps.

How can we get Excel to:

If we're in column C
    When Excel detects CR/LF
        If the cell was not empty
            Append a new line to the contents of the cell
        Append the scanned data to the contents of the cell
        Stay in that cell ready for the next scan
Then they can press an arrow key, if required, to get out of the cell.
-- adTHANKSvance