So, what I ended up doing was cutting two triangles for the space between the arm and body of Lindsays shirt when the arms are held out at ninety-degree angle from the body. Then I drew little wing tips and cut them out. Then I just hot glue gunned it along the sides of the body of the shirt and along the arm. It's probably not a long term stick, but it should work for Halloween. It looks cute while laying on the floor--I hope it looks as cute on Lindsay. :-)
Then I glued little bat ears onto a headband we bought for cheap. It kind of looks like cat ears, but hopefully the wings will convince people otherwise!
Overall, I think it will work. The real test is how well the picky eldest daughtr likes it all!!