Hi, from KC.

The ease/difficulty of altering a kilt depends on how the kilt was made. If you have a traditional, knife pleated kilt, it will be good quality and most likely the extra material around the waist has been removed. Couple ways to tell: are the pleats sewn from the hips up to the top of the kilt?

Is there a lining? Pictures would help here.

There are two easy ways to adjust the kilt: moving the buckles or moving the strap. There may be enough to make the adjustment. The bad side is the center of the apron will not be the center of the kilt. This is why you don't want to do too much alterations to a kilt. They might start having problems because the apron edge will not cover the underapron and the inverted pleat may bulge.

Does it have two buckles on one side? You might want to let a little out in the hips too.