I found a workaround for the time being. If you select the region you want to link (source), then copy it. In your new workbook you right click and select paste special, then select paste link in the bottom left hand corner. It will link that region to the new excel file. This works fine except it's not dynamic. The link won't work if they type something beyond that region. So let me know if you can think of anything.

Thanks
Andy