To make a mermaid skirt, first make a straight skirt. Pull the bottom of the straight skirt tightly around the doll’s knees with the overlap in the back and tape in place. Then prepare a circle skirt but instead of putting it around the doll’s waist, put it around the bottom of the straight skirt and tape in place in the back.
The circle skirt won’t always fit all the way around the doll’s knees. I either leave a gap if it as small one, taping both ends of the circle skirt to the bottom of the straight skirt, or take a piece from another circle skirt and insert it into the gap and tape everything together.
You can add a small circle skirt on top of the large circle skirt for a layered look.
You can use the small circle alone or the straight skirt over skirt for the mermaid skirt.
Add another circle skirt around the doll higher up for a two tiered skirt.
Add a circle skirt second circle halfway between the top of mermaid skirt circle and the doll’s waist then add one to the waist and you get this three tiered skirt.