Two questions for the more experienced DIY-ers out there.

First, I'm working on my first xkilt and either I'm missing something when reading the instructions or just not getting it with one thing. I've got the material hemmed and was ready to start marking out the pleat structure when something just didn't feel right. The instructions discuss the the first and last inner pleat folds, which makes sense. What confuses me is the diagram call for a 12" under apron pleat after the over apron. How do you determine the size of this under apron pleat? My over apron is going to be 11". Just looking for some clarification or did I miss something later in the instructions that explain this.

Second, my wife and I have been discussing making mini-xkilts for our sons out of the extra material from mine when it is complete (and there will be more than enough for me to do another xkilt and still make theirs after this first one is done). My question for this is, what would you recommend for changing the sizing of the pleats and the aforementioned under apron pleat for the kiddies. I'm looking at a rump size (with diapers) of 18 and 21 inches or there abouts for the two boys.

And before anyone says a thing, pictures will come when the job is complete. I am trying to document the process with pictures for a big post when complete.