Adapt skirt pattern to bigger size

I am looking for an easy begginner skirt pattern to make for my girls.
I saw the one I like in the May 2006 issue of Creative Knitting pg.90.
The problem is it only gives directions for up to a 28" waist and if I measured correctly, my 7 yr olds waist is about 30 ".

I also like the one that is in the May 2005 issue of Creative Knitting pg.38-39 but it is designed to be worn on the hips and I want to make one to wear on the waist and make it muchlonger than the one they have in there. This daughter’s waist is about 38".
Thanks in advance for any and all help.