There are 3 top layers and an under frill which is visible, so I'm thinking first layer where it joins the bodice in the print with a plain piping at the seam, then 2 plain white layers edged with a piping trim made from the print, and edge the final layer in , don't know yet - blue lace or something, and then the under frill which is visible in the print. that way it will visually close the skirt and won't look like a petticoat.
If I alternate plain blue and white layers it runs the risk of looking like a bit fairground and predictable so I think I'll just stick to the plan.