An from StraightGrain shares a tutorial over at Sew, Mama, Sew! showing how to make a little girl’s bubble skirt. She includes a pattern for cutting the lining, with sizes based on child’s hip measurements. Get the how-to.
[photo from StraightGrain]

I am trying to make simple flower girl dresses from a picture my daughter saw. She liked the tank top style, full bubble skirt with ribbon sash above the waist.
I found a pattern that is exactly what she liked except it does not have the bubble skirt.
I am assuming that the bubble skirt is created by cutting the lining a few inches shorter than the garment fabric, allowing a couple of extra inches of length and finishing the finishing the hemline before attaching the lining and garment fabric to the bodice of the dress.
I can just experiment, but do you have any suggestions?