I prefer
Olive.
I was discussing it for some reason with my folks the other day. We came to the conclusion that
Olive is very 'ethnic' (oh, the irony) and that, as my mother said, "there are goddamn thousands of Olivias". I mentioned liking
Olive and we all agreed it was the better name.
Willow Madeline Olivia is okay.
Willow Madeline Olive is better in my view.