I just draw something quickly, because I want to make sure I explain well what I saw. If wear skirt and just panties inside, when side down, the girl should sit like the first position. This is how I was taught when I grew up. Because when the leg is like that, nothing can be see. But sometimes girls will sit in the second or third position when sitting down. This is because very natural especially when there is a step when we sit down. Also easy to sit like this if we are using mobile phone or eating something. But if sitting like this, there will be some panties see by others if standing in front. This is what I saw from the two women. The second position will reveal panties like a triangle shape, but the last one will see it more which is probably the worst

Also sorry I'm not good painter, maybe hard to understand my drawing

Your drawing is understandable! I like seeing women sit like 2 and especially 3

Gosh I love to see this sort of thing and it's even better if there is a bit of pussy lip hanging out. I saw something like this while I was at work a few months ago a woman sitting on the top step just like you say and I could see straight down her fanny hole, a bit of lip hanging out, I almost cum in my pants. If I wasn't working I probably would of asked her if I could lick it lol. Gosh it was an hot sight, I needed a sit down after that my legs had turned to jelly.