Thanks for the help.
I have both the .bin and the .cue, and the extra file I want to add. I've opened the bin and "dragged" the extra file from the explorer window in the lower right to the opened image file in the upper right.
Magic ISO says it won't "burn" files larger than 300 Mbyte, so I'll have to get the real version.
But I want to make sure that I followed your directions correctly, and also, what I would rather do is create a modified image file first, before burning it to disk, as I also archive image files to DVD.
Will Magic ISO make a modified image file and if so how?
Thanks again for your help,