I applied this to the address fields which does now allow me to mass update.
However, as the street field is text area it does not allow entering a carriage return line feed (or at least I haven't found a way) so you can't break the content into separate lines in the field
The other option which apparently does work is to use export/import - seemingly if you enter Alt-Enter after each line in Excel this will be retained in the .csv and the import will bring that in correctly.
However this is not an efficient process for regular small changes.
If anyone else has better solution would be happy to hea rit.
