Could her address be rue Miron instead of Miroy? There is no rue Miroy in Nice, in fact the only one I can find is in Quebec. I do know that there are apartments at 7 rue Miron in Nice. I can send you a picture of them if you'd like.
I'd be happy to translate the letters for you. Do you have a scanner or know someone who could scan them for you?
I'll see what I can find about the Denise you located the family tree for.