If the kilt has a buttonhole, moving the left side (buttonhole) buckle won't do anything to solve the problem. If you move the buckle that's next to the buttonhole, you still can't get the strap to go any farther through the hole, because it's stitched firmly to the underapron. You can't, therefore, get the underapron any tighter if you move the buttonhole buckle.

What you have to do is move the underapron _strap_ instead of the buckle. Moving the underapron strap toward the center of the apron allows the underapron to be buckled more tightly.

And, no, removing the lower buckle and strap is not a problem. They are cosmetic, rather than functional. The kilt that I just made for Longhuntr has only one buckle and strap on the apron edge.