I am looking at the pair that Liesl made on her blog and it said lightweight twill. I ordered a lightweight twill called french twill and the description said 4.5 oz. but it is very lightweight for the pants almost like a summer fabric. It doesn't look as substantial as the fabric she used. The other twill fabric weights are 7oz. that is called medium weight and 8.2 called medium heavy in the description. I am sewing them for a 15 month old. Can anyone suggest a weight that would work?