If they told you there is not enough material in a 36" waist kilt to have it remade to a 40" waist, all that means is that they don't want to do it.

I'm assuming this is a standard 8 yard kilt, right? So it realistically probably has between 7 and 8 yards of cloth in it.

If I can make a kilt from 4 yards of cloth for a man with a 40" waist, then you should easily be able to re-make your 8 yard kilt to fit you.

They might mean that it could be more effort than it's worth -- but don't let them tell you it can't be done.

Aye,
Matt