Reference for those that dont know; Please always post one in the future
Chiffon could work...for parts, but its really not an ideal fabric for a structured dress. Your friend will also need a hoop skirt, probably about 4-6 hoops in which you will need to fit the dress over.
There really aren't patterns out there for this. Maybe something basic to start with the underskirt (white) but not the pink, which starts as a princess seam top and ends very wide in order to make the drapes and bustle.