I find that I have to lift the inner fold of the under apron pleats about 1/4 of an inch higher than the top of the aprons. This pulls the outer fold into place when the kilt is being worn.

Pleats gape when the inner fold is pushing towards the outer one, and by lifting it a little the push is counteracted. The push is a feature of wrapping a mostly two dimensional garment around a three dimensional body.

As the kilt is already completed try making a small horizontal dart in the inner fold, horizontally and as close to the waistband as you can and hold it with a few stitches. If that cures the problem then you can experiment with different sized darts to see how much lift you need to put into the pleat on the next kilt.

Anne the Pleater :ootd: