I'd do a mash-up and go with Janjoet. I'm serious. It's the best way, take an element of all three names and put them together. So when she tells people her middle name, they'll be like "Whaat?" and then she will have to tell them how she came by her unique middle name, and she'll have to mention the three women,
Jane,
Joanne, and
Janet, whom she was named after, and therefore, those three women will be mentioned much more than they ever would be if you had used some conventional name.
I'm totally serious. I want to emphasize that, because I know it will be very easy to take this in a humorous vein or to think that I'm ridiculing you or something, but I'm not, really. And I really think that almost anything goes for a middle name.