Well I guess you should be asking yourself if it's right. In my opinion NO it is not right, that to me would be a big problem that needed to be solved asap.
If she is deliberatly showing them - lifting her skirt and saying look here boys - then its not OK but if she is wearing a short skirt that accidently rides up or is in a similar situation which she corrects and it so happens a boy got a glimpse then thats not a problem
No tht is disgusting don't let her do tht
If she does it on purpose, it is NOT right. Your daughter has to learn modesty. You as a parent should teach her ladylike behavior. Showing boys her knickers is NOT ladylike.
Its part of growing up can't you remember girls showing you their knickers I do let her grow up her way
It's common sense...NO! That's only going to further show other parts which is not her niks....